Keywords

1 Introduction

The existence of variety among and within the living world—especially in agricultural plant, is known as biological diversity. It is necessary to break down biological diversity into three main categories, including genetic variety, species diversity, and ecological diversity. The presence of variation in heritable features within a population of a certain species is referred to as genetic diversity (Keshta et al. 2022). The term “genetic variation” refers to variations in DNA sequence, biochemical properties, physiological, and morphological traits including plant height, flower location, bloom color, and other various functions. Ramanatha and Hodgkin referred to genetic variety as the existence of variation in alleles, genotypes, the outcome of how they function (phenotypes), and the total of the genome (Yusuf and Daryono 2021). Using genetic variety is important for developing cutting-edge agricultural plant improvements. Because agricultural species have limited genetic variety, they are more vulnerable to newly developing diseases and other factors that reduce yield, which has a major negative impact on adaptability (Seyed Hajizadeh et al. 2022). The main force for evolutionary diversification and the source of phenotypic diversity is genetic variation. To address global concerns that influence food security, sustainability, and climate change adaptation, plant breeders employ variety in genetic resources to create new and improved crop cultivars (Swarup et al. 2021). Phenotypic variation, or variations in observable qualities within a population, results from genetic diversity. Plants experience increasingly frequent genetic and epigenetic alterations as a result of the dynamic and evolutionarily labile structure of plant genomes. This increased genetic and epigenetic diversity is seen even across cultivars of the same species (Lloyd and Lister 2022). Plants with more genetic variety have a remarkable capacity for rapid environmental adaptation. Crop improvement projects are successful when they successfully discover and incorporate genetic diversity from a variety of plant genetic sources, such as landraces, wild relatives of cultivated cultivars, recently generated cultivars, elite and/or mutant plants, and germplasm collections (Kronholm 2023). Plant breeding is still a time- and resource-intensive process, although several genomic tools and breeding techniques have increased the efficiency and precision of integrating genetic variation into marketable crop cultivars (Mishra et al. 2023a).

Long-term research has been done to identify the hereditary variations among vegetable and fruit species in light of their agronomic and morphological properties. Genome-wide association studies are the most common and productive technique for studying the connection between genetics and phenotype (GWAS) (He and Gai 2023). (Fig. 1). They have been shown to be beneficial in a number of major crops including rice (Oryza sativa L.), corn (Zea mays L.), and barley (Hordeum vulgare L.). However, there are still some drawbacks: (1) uncommon alleles are undetectable; (2) alleles with small phenotypic effects are difficult to identify; and (3) even the most significant SNPs are not necessarily the best predictors for a particular trait GWAS (Sabourifard et al. 2023). A statistical model is used to compute the genomic estimated breeding values (GEBV) of the population’s dominant individuals, which is the foundation for the marker-based selection technique known as genomic selection (GS) (Haristoy et al. 2023). In any case, the pattern of genetic variability in plants is complex and may be influenced by a variety of factors, such as the crop production system, plant development, the method of distributing seeds, geographical dispersion, and the ability of the plants to group together based on similar features (Štrbac et al. 2023). The degree and distribution of genetic diversity within a species of plant is influenced by factors such as the plant’s breeding practices, pace of development through time, topographical characteristics, historical barriers, and usually a variety of human causes. Molecular marker technologies, which are unaffected by climatic variables, are therefore one of the most significant methods employed today (Pandey et al. 2023).

Fig. 1
A flow chart for G W A S frameworks like S N P catalogue, population structure Q matrix, and phenotypic data point. This leads to Q T Ls and genes. S N P highlights single base changes.

Three frameworks are used in genome-wide association studies (GWAS): (1) the list of single-nucleotide polymorphisms (SNPs) derived through diversity assessment; (2) population structure and allele frequency spectrum (Q matrix); and (3) phenotypic data points for each person in the population

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The ability to identify genetic material in cultivated crops using molecular markers has made significant strides. The use of inter-simple sequence repeat (ISSR) markers in the molecular marker approach has tremendously aided research into the population structure of biological samples from different plant species (Bhattacharyya et al. 2023). The main reasons these markers are used are their quickness, productivity, repeatability, and exceptional capacity to distinguish a mind-boggling number of polymorphisms in a specific group (Rajpal et al. 2023). More importantly, molecular markers are essential tools for assessing the genetic variations between the genetic makeup of plants and living tissues or seeds that might be utilized to create new plants, resulting in marker-assisted selection. The following additional molecular markers have been successfully used in studies of diversification: SSRs (simple sequence repeats; Musa spp.) and Restriction fragment length polymorphisms (RFLP, wheat, cassava or Puntius spp.), barley or common bean (Mishra et al. 2023b). Projections show that climate change will make conditions unfavorable for cultivating many of the current crop cultivars, thus jeopardizing global food security. In agricultural regions across the world, extreme weather is becoming more prevalent (for instance, higher and lower than usual ambient temperatures and more intense rainfall as either floods or droughts), which impacts crop planting dates and introduces new plant diseases and pests to an area (Salgotra and Chauhan 2023). Due to a wet spring (April through June) in North America, only 49% of maize and 19% of soybeans were planted on time in 2019, compared to the averages of 80% and 47% for maize and soybean “on-time planting” for the preceding 5 years (Sedghi et al. 2023). In order to deal with these uncommon on-farm challenges, plant breeders must develop crops that are more robust to climate change and have higher capacity to withstand intense and frequent seasonal change. Comparatively speaking to upgrade crops for moderate and predictable seasonal fluctuations, developing crops and cultivars suited to flourish in harsh and changing settings is a distinct task for plant breeders (Rabin et al. 2023). For instance, the three most prevalent maize diseases in the U.S. at the time were Goss’s wilt (Corynebacterium michiganense ssp. nebraskense Schuster, Hoff, Mandel, and Lazar), anthracnose stalk rot (caused by Colletotrichum graminicola Ces.), grey leaf spot (caused by Cercospora zeaemaydis Tehon and Daniels), 40 years ago (Osdaghi et al. 2022). Due to the diseases’ rapidly worsening effects on crop productivity, which range from 6.1% (0.65 t/ha) yield loss from anthracnose stalk rot to 11.6% (1.25 t/ha) yield loss from Goss’s wilt, nearly all commercial maize breeding programs now focus on creating cultivars with resistance to the aforementioned diseases (Osdaghi et al. 2022). The cultivation of sweet cherry (Prunus avium L.) is an illustration of how exposure to extreme weather impacts production. Below-freezing weather in 2002 and 2012 caused the cherry blossom pistils to freeze, which led to a disastrous loss of the cherry harvest (Spanoghe et al. 2022). After successfully finding and transferring the “late bloom” trait from sour cherry (Prunus cerasus L.) into sweet cherry, cherry breeders were able to avert the crop loss. Plant breeders used the genetic variety offered by cultivars outside of their regular breeding germplasm collections in both crops to address the issues of avoiding yield loss (in maize) and crop loss, which are connected to food security (in cherry) (Bohra et al. 2022).

Vegetables and fruits are among the most significant crops in the world, contributing not only to food security but also to nutrition security. This is especially true when used as a food source for local and regional development (Imathiu 2021). It is nothing new; there are several examples of how they contribute to a diet that is socially acceptable, economical, sustainable, and nutrient-dense. Indigenous fruits and vegetables are those that have been consumed for a very long time or that have been introduced recently and are those that are grown locally (often using traditional practices). Despite not falling under a specific category, research organizations, food processors, marketers, and consumers frequently overlook and underutilize these foods. Evidence from several sources demonstrates that eating a variety of fruits and vegetables also significantly improves health outcomes. Increased intake of fruits and vegetables, particularly indigenous kinds, is expected to help reduce the global dietary shift and its adverse effects on nutrition and health. Because of this, research into the genetic variety and preservation of fruits and vegetables for suitable use is a necessary endeavor for mankind (Wijesinha-Bettoni and Mouillé 2019).

2 Significance of Genetic Diversity

The wide foundation of degree genetic divergence is what largely drives crop development. For the creation of excellent cultivars in agricultural improvement, genetic variety is of utmost importance. As opposed to the crossing of genetically identical materials, distinct genetic materials are predicted to perform better and produce more attractive hybrids. The genetic variability analysis, which is an excellent indication of genetic variety, is the foundation of the Mahalanobis D2 statistics, which exhibits a highly effective methodology. In order to verify this technique, it must be tested on a variety of crops. The presence of genetic variation in plant populations is useful for conservation and breeding programs (Salgotra and Chauhan 2023).

Plant genetic diversity provides researchers with the chance to create new, enhanced varieties with desirable features that satisfy the preferences of both farmers and breeders. As is well known, scientific plant breeding begins with the use of naturally occurring variety among crops. But as time went on, genetic variation decreased as a result of (1) biased breeding practices that concentrated on improving a small number of characters (yield and its component characters), (2) frequent use of a small number of carefully chosen parents in varietal development programs, and (3) introduction of a small number of varieties that increased genetic similarity between contemporary crop cultivars. In order to feed the world’s alarmingly rising population, crop genetic variety is becoming increasingly important (Zhang et al. 2023).

As the climate factors are changing and negatively affecting agricultural plants’ natural growth and development, plant breeders are now concerned with developing climate-adapted cultivars. The prevalence of desirable alleles is closely correlated with the presence of genetic diversity, which aids in the development of varieties that are climate adaptable. As a result of climate change, drought stress is becoming more unpredictable and severe, endangering the sustainability of agricultural production and food security. Breeding strategies can broaden the genetic variety of stress tolerance and increase yield under stress by incorporating the adaptive natural genetic variants (Salgotra and Chauhan 2023). High yields of farmers’ and breeders’ desired better quality cultivars are made possible by genetic variety. The creation of prospective variations resistant to new illnesses, insect pests, high heat, and extreme cold also heavily relies on genetic variety. The creation of variations for certain qualities, such as the tolerance of abiotic and biotic stressors and quality enhancement, is facilitated by genetic variety. Genetic variety loss was listed by the Food and Agricultural Organization as one of the most important environmental issues. It is essential to increase agricultural output by protecting and preserving the genetic variety of crops, and the producing environments’ management techniques need to be changed. Therefore, knowledge of genetic variability is a key component in selecting genotype that can withstand the changing environments (Boria and Blois 2023).

3 Variability and Adaptability

Crop species with the most genetic diversity have more opportunity to increase their ability to adapt to environmental changes. A genotype that is more adaptable will do better in any given environment. In the discussion of food security, adaptation to climate change is one of the most important challenges. Crop plants are subject to a wide range of environmental, biotic, and edaphic conditions that all have a role in their ability to adapt. Genotypes, environment, and genotype-environment interactions all contribute to the phenotype (Christenhusz et al. 2023). Crop plant development requires genotype × environmental interaction, which assesses the improved genotypes in various situations. The genotype by environment interaction leads to inconsistent performance across contexts for the various genotypes. Crop plants’ growth and development are impacted by intricate interactions between environmental (E) and management elements (M). As genetic variety provides the crucial foundation for long-term genetic gain, breeding programmers should tightly control the strength of selection throughout improvement. The availability of genetic variation within and across species determines how adaptable an organism is and how it affects genetic diversity (Raman et al. 2023).

The evolutionary mechanisms that influence a population’s gene pool include selection, mutation, gene flow, and genetic drift. Many factors contribute to genetic diversity. Many of them are listed below:

  1. (a)

    Evolution: Agricultural evolution may be defined as the evolution of crop plants over time as a result of artificial and natural selection as well as current breeding techniques. Evolution began with wild forms and progressed via several procedures to produce the intended domesticates. The current diversity of plants emerged from the oldest and most rudimentary species through a process known as evolution. By progressive processes, evolution is transforming genetic variety, which ultimately produced new crop species. Since 1859, Charles Darwin’s theory of evolution has been dictating that diversity exists in the initial population of plants and that the best-adapted individuals survive and reproduce in increasing numbers over time. Indeed, domesticated plants offer an alternate source of genetic resources for the development of genome architecture in evolutionary genetics (Merrick et al. 2023).

  2. (b)

    Domestication: The process of domestication involves the selection of favorable qualities while ignoring other undesirable ones, which led to a decrease in the frequency of ignored alleles. Domestication is the process of turning wild ancestors into cultivated species via ongoing selection for beneficial crop plant features in order to meet human need. Plants have been domesticated over the world in various agroecological conditions for various desirable features that the growers have requested. In order to secure the security of food and nutrition, crop plants with the appropriate features are artificially selected through domestication. In the process of domesticating agricultural plants, morphological and agronomical traits are genetically altered (Baekelandt et al. 2023). Domestication is the adaptation of high yielding varieties with improved nutritional quality, resistance to biotic and abiotic stresses, large seed and fruit sizes, non-shattering, a decrease in seed dispersal mechanisms, a more compact growth habit, and early matured crop plants. Crop plants have emerged from wild plants throughout the domestication process through artificial selection in order to meet a specific human need. Wild species are altered through artificial selection of agricultural plants, leading to their domestication (Vercellino et al. 2023).

  3. (c)

    Plant breeding: Plant breeding has a significant influence on food production and will always be important for ensuring global food security. Crop development depends critically on genetic variety since cross-pollination of genetic components from different origins demonstrates superiority over closely related species. To address the greatest genetic production potential of the crops, plant breeding principally relies on the availability of significant genetic variation and the successful exploitation of this variation through selection for improvement. Hence, plant breeding began earlier with plant domestication in order to create genotypes that were superior in terms of production, resistance to diseases and pests, and many other features. Due to agricultural plants’ restricted desires for additional enhancements for many desired features, plant breeding has reduced genetic material diversity (Varga 2023). Mutation: Genetic variety is largely produced via mutations, which are the primary source of genetic variation. In terms of crop species genetic modification, mutation can have positive, neutral, or negative effects. Mutation is the term used to describe the sporadic aberration of genetic resources such as DNA, RNA, and protein in cells that results in rapid heritable alterations in genetic variety. To feed the growing human population, genetic variety must increase, and mutations play a significant part in this process. Genetic diversity changes mostly as a result of mutation. Genetic variation, which depends on the frequency and variety of alleles among individuals within a population or a species, is known as genetic diversity (Salgotra and Chauhan 2023). The formation of sustained genetic variation, which is used to further progress, is fueled by mutation. While traditional breeding methods tend to reduce genetic variety for long-term improvement, induced mutagenesis increases genetic diversity. The use of mutant breeding is greatly increasing agricultural genetic diversity by enhancing crops to increase populations’ standard of living (Huang et al. 2023).

  4. (d)

    Migration: Crop plants travel both within and across species during migration. In species that have the ability to reproduce vegetative, it happens directly through vegetative propagules such as suckers and rhizomes as well as seed and pollen dissemination. On the other hand, migration is about gene flow, which happens when people move from one place to another and results in the mixing of two or more populations’ genes through the distribution of pollen and seeds (Copenheaver et al. 2023).

  5. (e)

    Selection: Plants are often chosen from a population based on their phenotype, which consists of both heritable and nonheritable elements. Crop genetic improvement depends on the kind and degree of genetic diversity present in the population as well as the nature of the relationship between yield and its constituent parts. This allows for the simultaneous selection of several yield-related features. Ample diversity offers choices from which choices for enhancement and potential hybridization are made (Chowdhury et al. 2023).

4 Effects of Genetic Erosion

Genetic erosion is the loss of genetic diversity over time and in a specific place as a result of a variety of circumstances. The loss may involve a single gene or a group of genes. Genetic loss is the aging process that results in less genetic variety. The modernization of agriculture, which involves the replacement of landraces with new, better kinds, is the main source of genetic loss. Plant breeding efforts are increasingly hampered by the loss of genetic diversity (Salgotra and Chauhan 2023). Crop, variety, and allele levels are the three places where genetic loss might take place. Genetic loss is mostly caused by climatic changes, deforestation, environmental degradation, urbanization, and the eradication of local land races. Three approaches can be used to measure genetic loss: (1) A crop, variety, or allele completely disappearing due to genetic degradation. (2) Genetic erosion as an alleviation in richness. (3) Genetic erosion as an alleviation in evenness. The population genetic variability markers, like Shannon’s index, cause genetic loss as a decrease in evenness. Frequencies of genes within a collection of genotypes in a given area are used to calculate genetic diversity. Because of dominant single genotypes or alleles, diversity level is decreased. Depletion of genes as a result of regeneration and storage procedures might lead to genetic loss during ex situ conservation (Zemede Lemma 2019).

5 Important Characteristics of Vegetative Propagated Crops

Horticulture, a significant aspect of agriculture, is the management, production, and sale of plants such as fruits, vegetables, flowers, decorative plants, medicinal plants, and fragrant plants. Horticulture has demonstrated its significance in a number of areas, including innovation, bettering land use, increasing crop variety, creating jobs, and ensuring the public’s nutritional security. Many horticultural crops are vegetative propagated, because it makes possible to fix and multiply favorable genetic combinations (Bulgari et al. 2021).

By using specialized vegetative propagules to undergo successive mitoses, vegetative or clonal propagation is an asexual reproduction technique that creates clonal populations (such as bulbs, corms, tubers, cuttings, buds, and apomictic seeds). The term “clone” refers to vegetative propagated material that is genetically homogenous and derived from a single individual (Ghosh and Haque 2019). In cultivating species such as potato (Solanum tuberosum), cassava (Manihot esculenta), and sweet potato (Ipomoea batatas), flowering and fertility are reduced and less significant in a fresh clone (Ipomea batatas). In these species, consumption and vegetative propagules are at odds. One hectare of potatoes requires two tons of tubers with an average weight of 50 g. Yet, fruit production and quality are essential qualities for species that are farmed for their fruit or reproductive organs (Fragaria × ananassa). Given that most of these crops combine sexual and asexual reproduction, there is a large genetic variation among species and populations, depending on how substantial sexual and asexual reproduction is in a given population (Acosta et al. 2021).

Vegetative reproduction enables the establishment of perfect chemical ratios, optimal ratios of essential traits, and increased genetic variance interactions. Moreover, it keeps up high levels of heterozygosity, a particular characteristic of such plants necessary for high hybrid vigor. Favorable spontaneous and induced mutations can be quickly found and spread. Unwanted crossings and the negative effects of wild to agricultural gene flow may be readily controlled. Cultivars that don’t produce viable seeds can continue to thrive thanks to vegetative propagation. Certain species can be replicated more rapidly, inexpensively, and conveniently by vegetative methods than they can through actual seeds (Bethke 2022). Propagation quickens the propagation rate and permits fast mass propagation of selected clones. Crops that reproduce vegetatively may exhibit substantial phenotypic variability due to transgenerational epigenetic inheritance. Variations in DNA base sequences or present environmental conditions do not cause an epigenetic alteration, which is a change handed down from mother to daughter cell (Verhoeven and Preite 2014).

6 Genetic Diversity in Vegetables

6.1 Asteraceae

The biggest family of flowering plants, the Compositae, contains more than 23,600 species and 1620 genera. With the exception of Antarctica, the family is found on all continents. A prominent leafy vegetable from this family that is used in salads is lettuce. The Mediterranean region, where lettuce has been grown since 2000 BC, is the primary region of origin (Pardeshi et al. 2023).

Asia, North America, central Europe, Spain, and Italy are the primary lettuce-producing regions in the globe. Studies were conducted to analyze the quantity and size of chromosomes in 15 distinct accessions of Iranian lettuce cultivars and variations. According to the study, all accessions contain nine chromosomes (n = 9), although there are morphological differences and heteromorphisms between the chromosomes. Most of the time, genetic diversity within the Asteraceae family stays obscure. As a result, more investigation is required to properly offer a thorough grasp of genetic variation in this family (Zheleva-Dimitrova et al. 2023).

6.2 Brassicaceae

One of the biggest plant families, Brassicaceae (Cruciferae), has 350–380 genera and over 3000 recognized species. Some of the most commercially significant crops in the world are members of this family, particularly those belonging to the genus Brassica L. (cauliflower, kale, cabbage, brussels sprouts, kohlrabi, and broccoli). All across the world, “cole” vegetables are cultivated and consumed. They originated from the wild cabbage plant Brassica oleracea L., which was domesticated. Several different types of leaf and root vegetables, oilseeds, and condiment crops may be found in these farmed species. Except for a few tropical regions, cole crops are cultivated everywhere. The most prevalent of them is cabbage, followed by broccoli and cauliflower (Sukeyna et al. 2023). Whereas cauliflower is more prominent in southern Europe, the United States, and Mexico, cabbage is more significant in northern and eastern European nations. B. oleracea was discovered in its wild form on the European Atlantic coasts, in Northern France, and in England. Related wild species are endemic to the Mediterranean region. It was outlined how Kale and non-heading cabbage were domesticated by the Greeks and Romans in the first century AD, spreading over Western Europe. Based on 51 SSRs and 715 alleles at polymorphic loci in 173 B. rapa accessions with a global geographic distribution, research was performed to examine the genetic structure and center of origin of Brassica rapa L. The Old-World group of the wild kinds, which included Europe, West Asia, and North Africa, displayed the greatest number and diversity of private alleles. It was thought that a second group, representing East Asia, had high levels of genetic variety as a result of a secondary center of diversification. The third group, however, was made up of immigrants to East, South, and Central Asia, who had little genetic variety. This family of roots crops includes turnips and radishes (Chen et al. 2023).

6.3 Convolvulaceae

[Ipomoea batatas (L.) Lam], also known as the sweet potato, is the sixth most important food crop and arguably the most significant plant in the Convolvulaceae family. South Mexico and Central America are where the sweet potato first appeared. Each breeding program must have access to genetic variety, and keeping in vitro or ex vitro germplasm collections will help to protect it (Fig. 2). The largest germplasm collection in the world, with more than 5500 cultivated I. batatas accessions from 57 nations preserved in 2000, is at the International Potato Center in Peru. For many years, other nations have maintained significant germplasm collections, such as the USA or Cuba (670 accessions) (Minemba et al. 2020).

Fig. 2
A photo of an agricultural land with patches of crops in the land. Each rectangular area encloses a patch.

Germplasm collections of Ipomoea batatas (L.) Lam help to conserve the genetic diversity for the future. (Source: INIVIT)

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Because of the rising food demand and to preserve genetic resources, research on sweet potato genetic variety is essential; 137 landraces from various regions of Puerto Rico (PR) were used in research to evaluate the genetic diversity of sweet potatoes using 23 SSR markers. The results revealed that sweet potatoes have high levels of genetic variation across PR, which may be attributed to the plant’s out-crossing tendency, human interference, and genetic make-up. The findings underscored how crucial it is to preserve this genetic variety for use in the future used 69 sweet potato cultivars from various parts of Latin America with amplified fragment length polymorphism (AFLP) markers in research to evaluate the genetic diversity of the crop in tropical America. Central America had the most genetic variety, while Peru and Ecuador had the lowest genetic diversity (Xu et al. 2022).

6.4 Cucurbitaceae

Cucumis sativus L., a member of the Cucurbitaceae family and commonly referred to as the cucumber, is a subtropical plant (Fig. 3). In order to shed light on the genetic foundations of cucumber domestication and variety, a genomic variation map was created by deep re-sequencing 115 cucumber lines obtained from 3342 accessions worldwide (which comprises of over 3.6 million variations). As a consequence, scientists were able to identify 112 possible sweeps for domestication, one of which contained a gene linked to the reduction of fruit bitterness, an important domesticated trait for cucumber. Compared to grain crops, fruit crops may have experienced fewer bottlenecks during domestication (Zhang et al. 2022).

Fig. 3
A photo of a cucumber plant and an inset image of the cucumbers collected.

Cucumber (Cucumis sativus L.) from the Cucurbitaceae family is a vegetable, which is used for salad. (Source: Courtesy of J. A. Cruz-Alfonso)

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Often found in tropical and subtropical regions is Momordica charantia L. It is also known by the names balsamina, Chinese cundeamor, bitter melon, and bitter gourd. Agronomic factors, 38 genotypes of the bitter gourd collected from different agroecological zones in India, and random amplified polymorphic DNA (RAPD) markers were used to quantify diversity at the morphological and molecular levels. They demonstrated via their research that the cluster pattern based on yield-related characteristics and molecular variation differed across bitter gourd cultivars and that genetic diversity based on yield-related attributes and ecological dispersion did not match. Tropical and subtropical climates are best for growing the pumpkin (Cucurbita pepo L.) (Bhatt et al. 2022). The phytochemical and genetic diversity of 3 naked seed and 11 real pumpkin seed types was assessed to find traits that might be used to choose parent progeny during breeding. It was established that breeding may be used to enhance the fruit and seed sizes, with the goal of improving the quality of the seeds. They discovered that C. moschata “Chaloos” was the best variety based on the characteristics of the fruit and seeds, such as the quantity of saturated and unsaturated fatty acids. The Mediterranean regions are home to the zucchini plant, Cucurbita pepo L. The genetic diversity in a group of C. pepo was evaluated using AFLP and sequence-related amplified polymorphism (SRAP) PCR-based methods. The two subspecies, ssp. ovifera and ssp. Pepo, may be used to categorize cultivars in accordance with the results of the cluster analysis. Compared to AFLP markers, the information from SRAP markers is more consistent with morphological variety and the evolution of morphological types. In addition, cultivars of different morphological types were categorized in the ssp. ovifera based on the color of the fruit, which may have given an indication of the varied developmental processes and degree of breeding in the accessions used in the experiment (Awasthi et al. 2022).

6.5 Malvaceae

Yellow vein mosaic virus was discovered to be sensitive in 42 genotypes, although disease tolerance was established in 11 kinds (de Santana et al. 2021).

6.6 Solanaceae

The genus Solanum is home to around half of the 2300 plant species that make up the Solanaceae family. Solanum tuberosum L., Lycopersicon esculentum L., and eggplant are the three most important cultivated members of the Solanaceae family (Solanum melongena L.). Asia, Europe, the Americas, and Africa are all popular places to find the vegetable eggplant (S. melongena L.). Although some Genetic analyses indicate that eggplant originated in Africa, it is generally accepted that it came from Asia, namely the Indo-Burman region. The subtropical species S. incanum L. is the source of eggplant; it is endemic to North Africa and the Middle East, and the majority of its wild relatives have been found in Africa (Kumari 2020). The largest type of eggplant has been found in India, where it has been grown for a very long time and is known as Brinjal. The World Vegetable Center is home to a substantial public eggplant germplasm collection with more than 3200 accessions collected from 90 different countries, which includes the three domesticated species and more than 30 wild relatives. Throughout the past 15 years, more than 10,000 eggplant seed samples from the Center’s collection have been sent to government and private organizations, including other gene banks (Dala-Paula et al. 2021).

They used ancient Chinese literature to investigate how the eggplant became domesticated (S. melongena). The earliest mention of eggplant was found in Chinese literature around 59 BC. The domestication of the eggplant was influenced by fruit characteristics including size, shape, and flavor. These qualities endured modifications in flavor, size, and size from microscopic to enormous fruits, leading to the production of a wider variety of fruit morphologies (Kılıç and Sertkaya 2019). The genetic diversity of modern cultivars of black eggplants was dwindling. By introducing black fruit materials from different origins, one could strengthen the genetic foundation of this cultivar type and improve one’s ability to take advantage of the heterosis created by crosses of genetically dissimilar materials employed RAPD markers to analyze 28 eggplant accessions from five distinct species in a separate research. With the use of 14 decamer primers, they were able to identify 144 polymorphic amplified products, demonstrating that there is a significant degree of genetic diversity among eggplant species. A tree diagram (dendrogram), which was created using the UPGMA technique to show the distance or dissimilarity between clusters, revealed that S. incanum was closest to S. melongena, followed by S. nigrum L. and only one accession of S. nigrum and S. surattense Burm. f. showing grouping with one another. After rice, wheat, and maize, the common potato (Solanum tuberosum) is the most widely farmed member of the Solanaceae family and a significant food crop. Potato cultivation and consumption by humans began around 8000 years ago in South America, specifically in the Andes. The largest genus is Solanum, which comprises 1500–2000 species and includes both the domesticated potato and its wild relatives. According to DNA analyses, the Andean potato prevailed in the 1700s, whereas the Chilean potato finally infiltrated Europe and took control long before the late blight outbreaks (Dala-Paula et al. 2021).

A rich, unique, and varied source of genetic diversity is provided by early potato cultivars and their wild relatives, which may be exploited to create potatoes with a range of characteristics. The different morphological traits include plant height, leaf and leaflet shape, flower color, stolon length, and the size, color, and shape of tubers, to name just a few. The largest potato collection in the world, kept at the International Potato Center (CIP) in Peru, has more than 5000 accessions of both cultivated and wild potatoes (Jo et al. 2022). Yet, because the world’s potatoes were developed from a small number of genotypes that originated in South America, they have a limited genetic base. Due to the scarcity of resistant cultivars after the late blight (Phytophthora infestans (Mont.) de Bary) outbreaks of the 1940s in Europe that genetic foundation shrunk even more. The Solanaceae family member Lycopersicon esculentum Mill. and its wild cousins display genetic diversity that results in heritable changes in fruit chemistry that may be used to discover genes that control biosynthesis and material buildup in the plant. The tomato is a straightforward berry-like fruit that thrives in tropical climates. The ethylene response factor SIERF6 was found to be crucial for the ripening process and carotenoid accumulation in their experiment using integrated transcriptome, genetic diversity, and metabolite profiles to investigate the influence of tomato fruit genetic variation on carotenoids. The presence of 953 carotenoid-related genes was explained by examining the link between carotenoid levels and gene expression patterns (Mattoo et al. 2022).

The tropical fruit Capsicum annuum L., sometimes known as the pepper plant, is a straightforward berry-like fruit that is a member of the Solanaceae family. Studies on 80 accessions of the domesticated and semi-wild C. annuum grown in Mexico, looked at the nucleotide sequences of these accessions at three single- or low-copy nuclear loci: Dhn, G3pdh, and Waxy. There was a 10% reduction in domesticate plant diversity compared to semi-wild plants and regional structuring in all three loci. Two hundred and sixty capsicum accessions from species in the Andes area were also described. The species C. chinense Jacq., C. baccatum (Willd.) Eshb., and C. pubescens Ruiz and Pav., which are frequently used as fresh vegetables and spices, were found to have intraspecific differences, and the principal cluster analysis revealed a distinct geographic division within the country for the Capsicum species (Reimer et al. 2022).

6.7 Umbelliferae

The root crop vegetable known as the carrot (Daucus carota L.), which is cultivated all over the world, is a member of the Umbelliferae family. In the form of vitamin A carotenoids, it is the principal source of antioxidants. Around 2500 species and 250 genera make up this family. Carrot farming is said to have started in Asia, and in the eleventh century, a primitive yellow-purple rooted variety was grown in the Afghanistan region. This variety differs from other varieties in terms of its leaf morphology, root color, and form. Large genetic variation is observed in cultivated carrot (Randa Zelyüt et al. 2022).

The genetic diversity between the eastern (Asian) and western (European) genetic pools in a sample of 88 cultivars of carrot was examined by using polymorphisms at 30 SSR sites. Two clusters of 17 and 61 accessions were identified using a Bayesian technique as the Asian and western types of accessions, respectively. According to the findings, the Asian gene pool has a higher level of genetic variety than the western gene pool. Morphological characterization also corroborated the findings of the SSR analysis. Also, 12 qualitative and 18 quantitative morphological features were used to assess the genetic diversity of Iranian carrot accessions. The Esfehan accession (1638.9 g/m2) and Kerman accession (1650.9 g/m2) had the highest average yield compared to the other accessions, according to the results. Comparatively to other accessions, the Shoshtar accession’s root color was purple, while the Esfehan accession had red and yellow roots (Dunemann et al. 2022).

6.8 Asteraceae

The Asteraceae (also known as the Compositae) is a large and diverse family of flowering plants, commonly known as the daisy or sunflower family. The family includes over 23,000 species in 1620 genera and is found throughout the world, with the highest diversity in the Americas. The family is also known for its many economically important members, such as lettuce, sunflowers, and artichokes. The family’s scientific name Asteraceae is derived from the genus Aster, and the Greek word “ἀστήρ” (aster), which means “star”. Asteraceae plants are recognizable by their composite flower heads, which are made up of many small flowers (called florets) arranged on a disk. The family includes a wide variety of plants, from herbaceous annuals and perennials to shrubs and trees. Some well-known examples of Asteraceae plants include sunflowers, daisies, chrysanthemums, and dandelions. Nearly 13,000 species make up the Asteraceae (or Compositae) family, which primarily consists of herbaceous plants but also includes some trees, shrubs, and vines. Lettuce, dandelions, cardoons, chicory, tarragon, absinthe, artichokes, and salsify are a few examples (Fu et al. 2023).

One of the key features of the Asteraceae family is its high level of genetic diversity. One of the main factors that has contributed is its ability to adapt to a wide range of environmental conditions. This has allowed different species to evolve and thrive in diverse habitats, from deserts and grasslands to wetlands and alpine regions (Abd-Alla 2022).

Another factor that has contributed to the genetic diversity of the Asteraceae is the family’s ability to hybridize and produce new, genetically diverse offspring. This is particularly true for some of the more closely related genera within the family, such as the sunflowers (Helianthus) and daisies (Aster). Additionally, the Asteraceae family includes many species that have evolved specialized mechanisms for seed dispersal, such as a pappus, a ring of bristles attached to the seed, which allows the seed to be carried by wind over long distances. This has also contributed to the family’s ability to colonize new areas and to diversify in new environments. Overall, the Asteraceae family is a prime example of the incredible diversity that can be found within a single plant family. The wide range of habitats, morphological and physiological characteristics, and reproductive strategies that are found across the family are all evidence of the family’s ability to adapt and evolve in response to changing environmental conditions. This diversity is critical for the continued survival and evolution of the family, as well as for the health of the ecosystems in which the family is found (Sharma and Lata 2022).

6.9 Liliaceae

The Liliaceae family, also known as the lily family, is a group of flowering plants that includes a diverse range of species, such as lilies, tulips, onions, and garlic. These plants are characterized by having linear or narrow leaves, and a range of brightly colored, often fragrant flowers. The flowers typically have six tepals (petals and sepals that are similar in appearance), and a distinctive reproductive structure called a stamen, which produces pollen (Singh 2022).

The Liliaceae family has been used for medicinal and culinary purposes for centuries. For example, garlic and onions, both members of the family, have been used for their medicinal properties and are also widely used as spices in cooking. Additionally, many species in the family are toxic if consumed in large quantities and should be used with caution. They are known for their attractive flowers, fragrant scent, and wide range of uses in both horticulture and traditional medicine.

One of the key factors that contributes to the genetic diversity of the Liliaceae family is the presence of many different subfamilies and genera within the family. For example, the genus Lilium, which includes lilies, has over 110 different species, each with its own unique genetic characteristics. Similarly, the genus Fritillaria has over 100 species, each with its own unique genetic makeup (Wang et al. 2022).

Another factor that contributes to the genetic diversity of the Liliaceae family is the presence of a wide range of different growth habits and ecological adaptations. For example, some species in this family are herbaceous and grow in moist, shady areas, while others are woody and can be found in dry, sunny areas. Additionally, some species are native to tropical regions, while others are found in cold temperate zones.

In addition to these factors, hybridization and polyploidy also play a role in the genetic diversity of the Liliaceae family. Hybridization is the process of crossbreeding between different species, which can result in the creation of new genetic combinations. Polyploidy, on the other hand, is the presence of extra sets of chromosomes in the cells of a plant, which can result in the creation of new genetic variations (Dehgan 2023).

Overall, the Liliaceae family is a diverse group of plants with a wide range of genetic diversity. This diversity is the result of a combination of factors, including the presence of a large number of different subfamilies and genera, a wide range of different growth habits and ecological adaptations, and the influence of hybridization and polyploidy (Dehgan 2023).

6.10 Chenopodiaceae

A complex collection of plants known as the Chenopodiaceae family comprises tiny trees, shrubs, and both annual and perennial herbaceous plants. They may be found in a variety of dry or salty settings, including deserts, salt flats, and other arid regions. The genus Atriplex, which includes the common orache, and the genus Chenopodium, which includes the goosefoot, are two of the most well-known members of this family. Other examples include spinach, beets, and Swiss chard (Pedrini et al. 2022).

The capacity of the Chenopodiaceae family to withstand extreme environmental conditions is one of its important traits. Several species in this family can endure high salt concentrations in the air and water and can live on salty soils. They can withstand high amounts of solar radiation and can live in places where there is little access to water. Several species in this family have grown invasive in various parts of the world due to their capacity to withstand severe environmental conditions (Morell-Hart et al. 2022).

The Chenopodiaceae family’s relevance to the economy is another noteworthy trait. Certain members of this family, like quinoa, are significant food crops, while others are utilized as feed for cattle. Several species’ leaves, seeds, and fruit are also utilized in conventional medicine.

The broad variety of morphological, physiological, and ecological traits displayed by many species within the Chenopodiaceae family are evidence of the family’s genetic diversity. This variety is the consequence of several processes, including hybridization, polyploidy, and adaptability to various environmental circumstances. They may be found in a variety of dry or salty settings, including deserts, salt flats, and other arid regions. They are characterized by their ability to tolerate harsh environmental conditions and their economic importance (Pedrini et al. 2022).

One of the key factors that contributes to the genetic diversity of the Chenopodiaceae family is the presence of a wide range of different growth habits and ecological adaptations. For example, some species in this family are annual and grow in dry, desert-like environments, while others are perennial and can be found in wetter, more mesic environments. Additionally, some species are native to tropical regions, while others are found in cold temperate zones (Razumova et al. 2023).

Another factor that contributes to the genetic diversity of the Chenopodiaceae family is the presence of a large number of different subfamilies and genera within the family. For example, the genus Atriplex has over 250 different species, each with its own unique genetic characteristics. Similarly, the genus Chenopodium has over 150 species, each with its own unique genetic makeup (Morell-Hart et al. 2022).

Hybridization and polyploidy also play a role in the genetic diversity of the Chenopodiaceae family. Hybridization is the process of crossbreeding between different species, which can result in the creation of new genetic combinations. Polyploidy, on the other hand, is the presence of extra sets of chromosomes in the cells of a plant, which can result in the creation of new genetic variations. Hybridization and polyploidy have been observed in many species of the Chenopodiaceae family, and it is thought that these processes have contributed to the genetic diversity of the family.

In summary, the family Chenopodiaceae is distinguished by a high degree of genetic diversity. This variety is the consequence of several processes, including hybridization, polyploidy, and adaptability to various environmental circumstances. The Chenopodiaceae family’s genetic diversity is further influenced by the existence of several distinct subfamilies and genera within it (Razumova et al. 2023)

6.11 Fabaceae

One of the largest and most diversified plant groups in the world is the Fabaceae family, usually referred to as the legume family. The family is now present on all continents with the exception of Antarctica, where it is thought to have originated. Species of the Fabaceae family may be found in a broad range of biological environments, including grasslands, deserts, and tropical rainforests. Important members of this family include common beans, peanuts, lentils, chickpeas, and lentils (Crameri et al. 2022).

The Fabaceae family is characterized by its unique floral structure, which includes a distinct keel and wing petals. The family is also known for its nitrogen-fixing ability, which allows many species to thrive in nutrient-poor soils. The Fabaceae family, also known as the legume family, is known for its high level of genetic diversity. This diversity is evident in the wide range of morphological, physiological, and ecological characteristics exhibited by different species within the family (Hassan et al. 2022). The genetic diversity of the Fabaceae family is the result of a combination of factors, including adaptation to different environmental conditions, hybridization, and polyploidy. One of the key factors that contributes to the genetic diversity of the Fabaceae family is the presence of a wide range of different growth habits and ecological adaptations. For example, some species in this family are annual and grow in dry, desert-like environments, while others are perennial and can be found in wetter, more mesic environments. Additionally, some species are native to tropical regions, while others are found in cold temperate zones. This diversity in the ecological niche allows the species to adapt to different environments and make use of different resources (Grygier et al. 2022).

Another factor that contributes to the genetic diversity of the Fabaceae family is the presence of many different subfamilies and genera within the family. For example, the genus Phaseolus has over 60 different species, each with its own unique genetic characteristics. Similarly, the genus Medicago has over 80 species, each with its own unique genetic makeup. This diversity within the family allows for different species to have different features and functions (Maroyi 2023).

Hybridization and polyploidy also play a role in the genetic diversity of the Fabaceae family. Hybridization is the process of crossbreeding between different species, which can result in the creation of new genetic combinations. This process is common in this family as many of the species are self-incompatible. Polyploidy, on the other hand, is the presence of extra sets of chromosomes in the cells of a plant, which can result in the creation of new genetic variations. Hybridization and polyploidy have been observed in many species of the Fabaceae family, and it is thought that these processes have contributed to the genetic diversity of the family (Kurmi 2023).

In conclusion, the Fabaceae family is characterized by a high level of genetic diversity. This diversity is the result of a combination of factors, including adaptation to different environmental conditions, hybridization, polyploidy, and genomic diversity. The presence of many different subfamilies and genera within the family also contributes to the genetic diversity of the Fabaceae family. This diversity plays an important role in the survival and evolution of the family, as well as its economic and ecological significance (Quach et al. 2023).

6.12 Poaceae

One of the biggest and most vital plant groups in the world is the Poaceae family, generally referred to as the grass family. This family is well renowned for its high level of morphological and ecological variety and has a wide range of species, from tiny annuals to big perennial grasses. We shall examine the Poaceae family’s description, history, and major producers in this article. Simple, long, thin leaves that are often arranged in a spiral pattern around the stem are the defining characteristics of the Poaceae family. The flat, rigid leaves often have parallel veins. The Poaceae family’s flowers are tiny and unnoticeable, and they grow in spikes called panicles. The flowers are wind-pollinated, which is one of the reasons why this family is so successful. The fruits of the Poaceae family are small and dry and are typically referred to as caryopses or grains. The Poaceae family also includes many important ornamental grasses, such as feather reed grass and maiden grass, which are used in landscaping and gardening (Abdullah 2022).

Many species of the Poaceae family have been used for medicinal purposes for centuries. Here are a few examples of medicinal importance of the Poaceae family:

  1. (a)

    Rice: The outer layer of rice, known as rice bran, is a source of antioxidants and has anti-inflammatory qualities. Traditional medicine also used rice bran oil to treat skin issues including psoriasis and eczema.

  2. (b)

    Wheat: Wheat grass, which is created from the young shoots of wheat plants, is frequently used as a nutritional supplement and is high in vitamins and minerals. It is used to treat skin diseases, blood issues, and diabetes and is thought to have anti-inflammatory and antioxidant qualities.

  3. (c)

    Barley: Barley grass is frequently used as a dietary supplement and is high in vitamins and minerals. It is used to decrease cholesterol levels, aid digestion, and it is thought to have anti-inflammatory qualities (Balicog et al. 2022).

  4. (d)

    Bamboo: Anti-inflammatory and loaded in antioxidants are bamboo leaves. They help to enhance blood circulation and cure skin disorders including eczema and psoriasis.

  5. (e)

    Sorghum: Traditional medicine uses sorghum to cure a variety of ailments, including diabetes, hypertension, and cancer. Furthermore, eczema and psoriasis are skin disorders that are treated with sorghum bran.

  6. (f)

    Oats: Oat straw, which is created from the stems of oats, is frequently used as a nutritional supplement and is high in vitamins and minerals. It is used to decrease cholesterol levels, aid digestion, and it is thought to have anti-inflammatory qualities (Huda et al. 2022).

The Poaceae family, generally known as the grass family, is one of the most varied and extensively dispersed plant groups on Earth, with over 10,000 species found in practically every ecosystem. The Poaceae family has a very high genetic diversity, and distinct species exhibit a wide variety of morphological, cytological, and molecular variation. The Poaceae family has a high level of morphological variety, with variations in the inflorescence and spikelet structure, as well as stem and leaf size, shape, and color. For instance, although some grasses, like bamboo, have tall, woody stalks with wide, flat leaves, others, like rice and wheat, have upright stems with long, thin leaves. Moreover, there are several varieties of inflorescences, each with their own unique characteristics (Cheng et al. 2022).

Cytological diversity within the Poaceae family is also high, with variation in chromosome number and size observed among different species. For example, some grasses such as rice have a diploid chromosome number of 2n = 24, while others such as corn have a higher chromosome number of 2n = 40. Molecular diversity within the Poaceae family is also high, with variation in DNA sequence, gene expression, and protein structure observed among different species. For example, there are many different types of genes involved in the regulation of growth and development, as well as in the response to environmental stress (Maclot et al. 2023).

One of the main factors contributing to the high level of genetic diversity within the Poaceae family is its wide range of habitats and climatic conditions. Grasses are able to adapt to a wide range of environmental conditions, from the harsh conditions of deserts to the lush rainforests, and this adaptation has led to the evolution of a diverse array of genetic variation. In addition to its high level of genetic diversity, the Poaceae family also has a high level of genetic plasticity, which allows different species to adapt to changing environmental conditions. For example, many grasses are able to switch between C3 and C4 photosynthesis, depending on the availability of water and light (Li’aini and Kuswantoro 2023).

The Poaceae family, with its high levels of genetic variety seen among many species, is, in conclusion, one of the most varied and extensively spread plant groups on Earth. A vast variety of habitats and climatic conditions, as well as grasses’ capacity to adapt to shifting environmental conditions through genetic plasticity, are the causes of this diversity. The Poaceae family’s genetic diversity is necessary for the sustained survival and production of these species in the face of environmental difficulties because it plays a critical role in the development and adaptation of this significant plant group (Devi et al. 2022).

6.13 Lamiaceae

The family of flowering plants known as Lamiaceae, or the mint family, is enormous and diversified. There are several well-known herbs in it, including sage, mint, rosemary, oregano, and basil, as well as numerous additional species that are used for decorative purposes. Although some species are shrubs or small trees, most of the plants in this family are annual or perennial herbs. The mint family is known for its opposing leaves and frequently square stems. The blooms are often tiny, clustered in spikes or clusters, and come in a variety of hues, such as white, pink, purple, and blue (Wilson et al. 2023).

The capacity of the Lamiaceae family to adapt to various settings is one of the key ways it exhibits genetic variety. This family contains species that can survive in a variety of environments, from humid, tropical locales to dry, desert places. For instance, certain mint species grow well in the arid, stony soils of the Mediterranean area, while others may flourish in the moist, shaded conditions of the rainforest. Genetic differences that enable various species to endure a variety of climatic circumstances, such as changes in temperature, humidity, and soil conditions, are the cause of this adaptability (Inanoglu et al. 2023).

Geographical isolation is another way the Lamiaceae family exhibits genetic variation. Because members of this family may be found all over the planet, many species have had time to develop and adapt independently of one another. This has caused various genetic features and characteristics to arise in various species, resulting in a wide variety of variation within the family. For instance, Mediterranean mint species are genetically distinct from Asian or North American mint species. With the evolution of distinctive genetic features, the Lamiaceae family also exhibits genetic diversity. For instance, certain mint species have evolved distinctive smells and scents, while others have evolved distinctive therapeutic characteristics. Genetic changes throughout time gave rise to these distinctive characteristics, allowing some species to differentiate themselves from others in the family (Rabin et al. 2023).

Due to its capacity to adapt to various conditions, geographic isolation, and the evolution of distinctive genetic features, the Lamiaceae family exhibits a broad spectrum of genetic diversity. The Lamiaceae family is a very intriguing and diverse collection of plants to study and enjoy because of their richness.

7 Conclusions and Prospects

The degree of genetic variety present among crop species determines how well breeding efforts for those species perform. The creation of improved varieties with regard to yield and other desired qualities depends heavily on genetic diversity. Fruits and vegetables are examples of horticultural crops that are commonly cultivated and consumed because of their advantages in terms of nutrition and food security. The sustainability of agricultural output and the preservation of genetic resources depend on the diversification of vegetable crops. Enough genetic variety must be used in order to produce superior hybrids and desirable recombinants. The genetic variety of farmed germplasm can be increased by inter- and intraspecific hybridization, and related wild species can also be crossed to combine desired features into a single individual. In addition, hybridization enhances the genetic variety for qualities that are underutilized or currently being underutilized in breeding efforts, which helps to lessen these crops’ genetic susceptibility (Peccoud et al. 2010).

Although it is a good strategy, using biotechnology in breeding projects is only practical for heavily farmed and eaten horticulture crops. For genotyping, choosing complementing parents for crossing, and spotting superior genotypes in the initial round of selection, molecular markers might be helpful. Thus, it is essential for the crop development program to characterize genetic resources using various statistical approaches. Improvements are mostly dependent on genetic variety for both qualitative and quantitative features. Rapid propagation techniques for smallholders and commercial growers should be made available through public expenditures in order to lower production costs and improve yield, quality, and food security. So, by offering a wide variety of crops that may be grown and enjoyed by people all over the world, diversification of vegetable crops significantly contributes to enhancing food and nutritional security (Yeken et al. 2022).