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Ex Situ Conservation of Plant Genetic Resources: Global Development and Environmental Concerns

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Abstract

Conservation of plant genetic resources is achieved by protection of populations in nature (in situ) or by preservation of samples in gene banks (ex situ). The latter are essential for users of germplasm who need ready access. Ex situ conservation also acts as a back-up for certain segments of diversity that might otherwise be lost in nature and in human-dominated ecosystems. The two methods are complementary, yet better understanding of this interrelation and the role of ex situ conservation in global environmental considerations is needed. Inclusion of ex situ conservation efforts within current environmental policies conserving global diversity would focus greater international attention on the safeguarding of these efforts.
... Many ex situ collections, however, have been founded based on comprehensive sampling in the native distribution area of plant species. This can give a better representation of the gene pool and reduce the potential for the processes of genetic erosion in successive generations [12,13]. Questions relating to these concerns are discussed in several publications about ex situ conservation and genetic diversity [14][15][16][17][18][19]. ...
... The results exhibited a complex genetic structure, with different degrees of admixture of the analyzed M. dubia germplasm accessions from eight river basins. Germplasm accessions from the 12 Amazonas, Itaya, Nanay, Napo, and Ucayali River basins showed some degree of admixture; that is, plant genotypes were assigned to multiple genetic clusters. Those germplasm accessions derived from the Tigre and Curaray River basins displayed moderate grades of admixture, mostly being assigned to clusters 5 (grey) and 9 (light brown), respectively. ...
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The Amazonian shrub Myrciaria dubia (Kunth) McVaugh, known as "camu-camu", produces vitamin C-rich fruits of growing commercial interest. However, sustainable utilization requires assessment and protection of the genetic diversity of the available germplasm. We hypothesized that the ex situ M. dubia germplasm bank assembled from eight river basins across the Peruvian Amazon would harbor substantial genetic diversity and have a genetic population structure. This study aimed to (1) develop new polymorphic microsatellite markers, (2) characterize genetic diversity and validate the hypothesis in the ex situ germplasm, and (3) construct a core subset representing maximum allelic variability. Sixteen polymorphic microsatellite loci were developed using an enrichment approach. The evaluation of 336 genotypes from 43 accessions originating from eight river basins of the germplasm bank corroborated this hypothesis, revealing high gene diversity, with observed heterozygosity ranging from 0.468 to 0.644 and expected heterozygosity from 0.684 to 0.817 at the river basin level. Analysis of molecular variance showed a higher genetic variation within accessions and river basins, at 73% and 86%, respectively, than among accessions and river basins, at 27% and 14 %, respectively. Bayesian clustering detected the presence of ten genetic clusters, with several degrees of admixture among river basins. The Putumayo River basin showed a clear genetic homogeneity. A core collection of 84 genotypes was constructed, thus covering 86.7% of the global allelic diversity. These results have important implications for M. dubia conservation strategies and breeding programs, in demonstrating a need for genetic connectivity between populations but preserving unique genetic resources in isolated basins. These results validate the expected levels of diversity and population subdivision in a crop and stress the need to secure genetically diverse germplasms, underscoring the importance of thorough genetic characterization for ex situ germplasm management.
... Biodiversity conservation is one of the critical global challenges, and ex situ methods 58 play an increasingly important role in this task (Cohen et al., 1991). One of the most 59 common ex-situ methods for plant conservation are seed banks, dedicated facilities 60 that store seeds of wild plant species, particularly the vulnerable ones (Peres, 2016). ...
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Premise Conservation seed banks are an essential tool for plant ex-situ conservation. However, seeds stored for long periods of time slowly deteriorate and lose viability. While seed longevity is known to vary between species, the extent of variability within species and the factors driving it remain unclear. Methods We focused on both inter- and intraspecific variability in seed longevity and its determinants. We studied 41 common grassland species and 188 seed accessions from across Europe. We exposed the seeds to artificial ageing conditions (60% RH, 45°C) and estimated the seed longevity (p 50 ), defined as the time required for viability to decline to 50% of the initial viability. We then tested the relationships between seed longevity and both species- and origin-specific factors. Results Variability in seed longevity was only slightly greater between species than within species, with species identity explaining 51.9% of the total variation in seed longevity among seed accessions, leaving 48.1% of the variation within species. In interspecific species comparison, seed viability was predicted only by initial seed viability, but unrelated to species-specific seed mass or seed chemical composition. Within species, seed longevity increased with the initial viability of the seed accession and mean annual temperature at the accession origin, but was unrelated to seed mass or precipitation in the origin, and the residual variance was substantial. Conclusion Our findings highlight that seed longevity on the level of individual seed accessions remains challenging to predict.
... Ex-situ conservation in gene banks is essential for safeguarding genetic diversity against potential losses due to environmental changes or cultural shifts. These gene banks act as warehouses for genetic material, available for future breeding and research purposes (59). Core collections represent a manageable subset of the genetic range of the base collection, enabling focused and efficient evaluation of traits. ...
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Sweet corn originated from Mesoamerica around 10,000 years ago; sweet corn’s distinctiveness lies in its genetic mutations sugary1 (su1), shrunken2 (sh2), and sugary enhancer1 (se1) that enhance kernel sweetness by inhibiting the average sugar-to-starch conversion. This transformation from an ancient staple to a globally beloved vegetable highlights sweet corn’s adaptability, high yield potential, and nutritional benefits, including its role as a source of carbohydrates, proteins, vitamins, and minerals. Advances in biofortification and genetic research have further enriched its nutritional profile, positioning sweet corn as a nutraceutical crop capable of addressing global nutritional deficiencies. Modern breeding techniques, including marker-assisted selection and omics technologies, have significantly accelerated the development of varieties with improved traits such as disease resistance, stress tolerance, and enhanced nutritional quality. Additionally, it is important to conserve sweet corn's genetic diversity for future crop improvement and adaptation. High-throughput phenotyping and genome-editing tools such as CRISPR/Cas9 have further accelerated sweet corn breeding, offering a sustainable solution to enhance yield and quality. This exploration shows sweet corn's agricultural importance, its potential to fight nutritional challenges, and the role of scientific advancements in securing its future as a valuable and versatile crop. This detailed review explores the history, genetic diversity, nutritional value, and modern advancements in the cultivation and breeding of sweet corn.
... Many ex situ collections, however, have been founded based on comprehensive sampling in the native distribution area of plant species. This can give a better representation of the gene pool and mitigate genetic erosion in successive generations [17,18]. Questions relating to these concerns are discussed in several publications about ex situ conservation and genetic diversity [19][20][21][22][23][24]. ...
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The Amazonian shrub Myrciaria dubia (camu-camu) produces vitamin C-rich fruits of growing commercial interest. However, sustainable utilization requires assessment and protection of the genetic diversity of the available germplasm. This study aimed to develop and apply microsatellite markers to assess genetic diversity and construct a core collection of M. dubia germplasm from the Peruvian Amazon. Sixteen polymorphic microsatellite loci were developed using an enrichment approach. The evaluation of 336 genotypes from 43 accessions of the germplasm bank, originating from eight river basins, was conducted using these newly developed markers. Genetic diversity parameters, including observed and expected heterozygosity, were calculated. Analysis of molecular variance (AMOVA) was performed to assess the distribution of genetic variation within and among accessions and river basins. Bayesian clustering analysis was employed to infer population structure. A core collection was constructed to maximize allelic richness. High genetic diversity was observed, with heterozygosity values ranging from 0.468 to 0.644 (observed) and 0.684 to 0.817 (expected) at the river basin level. AMOVA indicated significant genetic variation within (73–86%) compared to among (14–27%) accessions and river basins. Bayesian clustering detected ten genetic clusters, with several degrees of admixture among river basins, except for the genetically homogeneous Putumayo River basin. A core collection comprising 84 plant genotypes (25% of the full collection) was established, representing 90.82% of the overall allelic diversity. These results have important implications for M. dubia conservation strategies and breeding programs, in demonstrating a need for genetic connectivity between populations but preserving unique genetic resources in isolated basins. These results validate the expected levels of diversity and population subdivision in a crop and stress the need to secure genetically diverse germplasms, underscoring the importance of thorough genetic characterization for ex situ germplasm management.
... Ideally, the conservation of a threatened plant species occurs in its natural habitat with protection and proper management; however, ex situ conservation (e.g., conserving germplasm off-site in a protected area, seed bank, or botanical garden) is a complementary approach commonly used in conjunction with in situ conservation efforts. The primary goals of ex situ conservation are to safeguard against the loss of individuals and populations of a threatened species and to provide source material for population augmentations and reintroductions (Cohen et al., 1991;Falk and Holsinger, 1991;Kramer et al., 2011;Guerrant et al., 2014;Center for Plant Conservation, 2019). Ex situ conservation is particularly important for safeguarding species experiencing threats in their native habitat, including widespread habitat conversion, adverse land use practices, or reproductive failure (Pritchard et al., 2012). ...
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Premise Although ex situ collections of threatened plants are most useful when they contain maximal genetic variation, the conservation and maintenance of genetic diversity in collections are often poorly known. We present a case study using population genomic analyses of an ex situ collection of Karomia gigas, a critically endangered tropical tree from Tanzania. Only ~43 individuals are known in two wild populations, and ex situ collections containing 34 individuals were established in two sites from wild‐collected seed. The study aimed to understand how much diversity is represented in the collection, analyze the parentage of ex situ individuals, and identify efficient strategies to capture and maintain genetic diversity. Methods We genotyped all known individuals using a 2b‐RADseq approach, compared genetic diversity in wild populations and ex situ collections, and conducted parentage analysis of the collections. Results Wild populations were found to have greater levels of genetic diversity than ex situ populations as measured by number of private alleles, number of polymorphic sites, observed and expected heterozygosity, nucleotide diversity, and allelic richness. In addition, only 32.6% of wild individuals are represented ex situ and many individuals were found to be the product of selfing by a single wild individual. Discussion Population genomic analyses provided important insights into the conservation of genetic diversity in K. gigas, identifying gaps and inefficiencies, but also highlighting strategies to conserve genetic diversity ex situ. Genomic analyses provide essential information to ensure that collections effectively conserve genetic diversity in threatened tropical trees.
... Based on the IUCN Red List criteria and standards (version 3.1), this species is defined as endangered (EN) and requires urgent research and conservation efforts [1]. Therefore, it is of utmost importance to protect this species, as both genetic resource conservation and plant breeding require assessment of the genetic diversity and outcomes of endangered species [3,4]. To date, potential habitats, population structure, spatial distribution patterns, soil microbial community structure, functional diversity, and enzyme activities of R. pudingense plants have been reported in previous researchs [2,[5][6][7], the genetic diversity and population structure of R. pudingense population were still unclear, which may cause it difficult to plan conservation strategies for this R. pudingense. ...
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Background Rhododendron pudingense, firstly discovered in Puding county of Guizhou province in 2020, have adapted to living in rocky fissure habitat, which has important ornamental and economic values. However, the genetic diversity and population structure of this species have been rarely described, which seriously affects the collection and protection of wild germplasm resources. Results In the present study, 13 pairs of primers for polymorphic microsatellite were used to investigate the genetic diversity of 65 R. pudingense accessions from six different geographic populations. A total of 254 alleles (Na) were obtained with an average of 19.5 alleles per locus. The average values of polymorphic information content (PIC), observed heterozygosity (Ho), and expected heterozygosity (He) were 0.8826, 0.4501, and 0.8993, respectively, These results indicate that the microsatellite primers adopted demonstrate good polymorphism, and the R. pudingense exhibits a high level of genetic diversity at the species level. The average genetic differentiation coefficient (Fst) was 0.1325, suggested that moderate divergence occurred in R. pudingense populations. The average values of genetic differentiation coefficient and gene flow among populations were 0.1165 and 3.1281, respectively. The analysis of molecular variance (AMOVA) indicated that most of the population differences (88%) were attributed to within-population variation. The PCoA results are consistent with the findings of the UPGMA clustering analysis, supporting the conclusion that the six populations of R. pudingense can be clearly grouped into two separate clusters. Based on Mantel analysis, we speculate that the PD population may have migrated from WM-1 and WM-2. Therefore, it is advised to protect the natural habitat of R. pudingense in situ as much as possible, in order to maximize the preservation of its genetic diversity. Conclusions This is the first comprehensive analysis of genetic diversity and population structure of R. pudingense in Guizhou province. The research results revealed the high genetic diversity and moderate population diferentiation in this horticulture plant. This study provide a theoretical basis for the conservation of wild resources of the R. pudingense and lay the foundation for the breeding or cultivation of this new species.
... These invaluable genetic resources are now safeguarded in 1,750 genebanks worldwide (Engels, 2003;FAO, 2010). Most of these plant samples are conserved away from their natural habitats, forming ex-situ collections (Cohen et al., 1991). These collections play a crucial role in developing superior crop varieties, enhancing yields, improving nutrition, adapting to climate change, and bolstering resilience against pests and diseases (Westengen et al., 2018;Sheat et al., 2019;Baptista et al., 2022;Mba and Ogbonnaya, 2022). ...
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Crop diversity conserved in genebanks facilitates the development of superior varieties, improving yields, nutrition, adaptation to climate change and resilience against pests and diseases. Cassava (Manihot esculenta) plays a vital role in providing carbohydrates to approximately 500 million people in Africa and other continents. The International Center for Tropical Agriculture (CIAT) conserves the largest global cassava collection, housing 5,963 accessions of cultivated cassava and wild relatives within its genebank. Efficient genebank management requires identifying and eliminating genetic redundancy within collections. In this study, we optimized the identification of genetic redundancy in CIAT’s cassava genebank, applying empirical distance thresholds, and using two types of molecular markers (single-nucleotide polymorphism (SNP) and SilicoDArT) on 5,302 Manihot esculenta accessions. A series of quality filters were applied to select the most informative and high-quality markers and to exclude low-quality DNA samples. The analysis identified a total of 2,518 and 2,526 (47 percent) distinct genotypes represented by 1 to 87 accessions each, using SNP or SilicoDArT markers, respectively. A total of 2,776 (SNP) and 2,785 (SilicoDArT) accessions were part of accession clusters with up to 87 accessions. Comparing passport and historical characterization data, such as pulp color and leaf characteristic, we reviewed clusters of genetically redundant accessions. This study provides valuable guidance to genebank curators in defining minimum genetic-distance thresholds to assess redundancy within collections. It aids in identifying a subset of genetically distinct accessions, prioritizing collection management activities such as cryopreservation and provides insights for follow-up studies in the field, potentially leading to removal of duplicate accessions.
... Seed exchange among farmers may have easily spread these traits in the community of farmers growing Dumbja in the Paro district of Bhutan. This study supports the concept that ex-situ conservation is very useful in restoring lost materials to farmers (Cohen et al. 1991). Ex-situ and in-situ germplasm conservation methods are complementary. ...
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Farmers and consumers in Bhutan perceive that the quality traits of the popular, local, high-altitude rice variety Dumbja, which has been cultivated since ancient times, has deteriorated in terms of its phenotypic characteristics, particularly its taste and aroma. This four-year study therefore aimed to agronomically evaluate and compare accessions of the traditional Bhutanese rice variety Dumbja and a commonly grown improved cultivar with what is considered to be the official Dumbja variety. Fifteen accessions of the Dumbja variety—nine conserved in-situ by farmers and six conserved ex-situ by the National Gene Bank—were evaluated agronomically in a partially replicated design over four cropping seasons. The trials were conducted in Tshento, Paro district, a high-altitude rice-growing area, 2400 m.a.s.l., where the variety has been grown since ancient times. Trials identified significant differences for 1000 kernel weight, plant height, and tiller number, but not for grain yield. Compared with the improved cultivar used as a control, all 15 accessions were taller, with smaller kernels and, in some cases, with more tillers. As a group, the in-situ accessions were significantly shorter, with more tillers than the ex-situ accessions. Only one of the ex-situ accessions held by the National Gene Bank was recognized by farmers as the original Dumbja variety. The results are discussed in relation to in-situ vs ex-situ agrobiodiversity conservation strategies and also highlight the key role of farmers’ knowledge in restoring a traditional variety.
Chapter
Plant breeding originated in antiquity when humans domesticated crops about 10,000 years ago. Their efforts were advanced to a new level by early plant breeding pioneers armed with rudimentary information about reproduction and heredity. Then came Gregor Mendel, who laid down the scientific basis of heredity. Along with Charles Darwin's Theory of evolution by natural selection, classical genetics revolutionized the art and science of plant breeding in the twentieth century. However, the technologies of that period need to be improved to sustain the plant breeding industry in developing crop varieties for the twenty-first century. Not only is the global population on the increase, but the effects of climate change continue to modify the agricultural landscape, making the task of developing new varieties more complicated. As knowledge abounds, new technologies and techniques emerge to revolutionize plant breeding in the twenty-first century. Innovations notwithstanding, modern plant breeders must remain conversant with conventional plant breeding approaches that remain the bedrock of crop improvement. Modern tools help the breeding program to be more efficient and effective in getting a new and more productive variety to market more quickly. Conventional selection techniques, hybridization, and breeding schemes or methods are relevant today. Modern technologies like DNA marker-assisted selection, genomic-assisted breeding, whole genome sequencing, speed breeding, RNAi technology, and CRISPR/Cas9 genome editing technology are revolutionizing 21st-century breeding. This chapter reviews the evolution of plant breeding technologies and techniques and their successes, prospects, and challenges.
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Background Rhododendron pudingense, firstly discovered in Puding county of Guizhou province in 2020, have adapted to living in rocky fissure habitat, which has important ornamental, and economic values. However, the genetic diversity and population structure of this species have been rarely described, which seriously affects the collection and protection of wild germplasm resources. Results In the present study, 13 pairs of primers for polymorphic simple sequence repeats (SSRs) were used to investigate the genetic diversity of 65 R. pudingense accessions from four different geographic populations. A total of 254 alleles (Na) were obtained with an average of 139.6 effective alleles (Ne) per locus. The average values of polymorphic information content (PIC), observed heterozygosity (Ho), and expected heterozygosity (He) were 0.8826, 0.4501, and 0.8993, respectivelysuggesting high genetic diversity. The average genetic differentiation coefficient (Fst) was 0.1182, suggested that moderate divergence occurred in R. pudingense population. The average values of genetic differentiation coefficient and gene flow among populations were 0.1279 and 1.8984, respectively. The analysis of molecular variance (AMOVA) indicated that most of the population differences (89%) were attributed to within-population variation. The UPGMA clustering analysis showed consistent results with the genetic distance and genetic identity analysis, indicating that the genetic background between the populations of Wanmo (WM) and Puding (PD) were similar, while the populations of Zhenning (ZN) and Qinglong (QL) showed significant genetic difference. Conclusions This is the first comprehensive analysis of genetic diversity and population structure of R. pudingense in Guizhou province. The research results revealed the high genetic diversity and moderate population diferentiation in this horticulture plant. This study provide a theoretical basis for the conservation of wild resources of the R. pudingense and lay the foundation for the breeding or cultivation of this new species.
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Foreign assistance helps developing countries to achieve economic growth through wise use of natural resources. Conservation interventions and sustainable use of natural resources play a central role in this development. Conservation and utilization of genetic resources have traditionally proceeded as separate approaches. A conceptual approach to project design is presented encouraging greater interaction between those conserving crop genetic resources and those seeking their economic application in a sound land-use management plan. Projects illustrating this approach are being supported by the Agency for International Development. They suggest a paradigm for research and development allowing interdisciplinary activities targeting sustainable agriculture development. La ayuda extranjera contribuye a que los países en desarrollo logren un crecimiento económico a través del uso apropriado de sus recursos naturales. La interventión en la conservation y el uso sostenible de recursos naturales debe desempeñar un papel primordial en este desarrollo. La conservatión y utilization de recursos genéticos tradicionalmente se ha considerado como enfoques separados. Presentamos un enfoque conceptual para proyeetar el diseño, estimulando mayor interactión entre esos recursos de productos geneticos de conservación y aquellos que buscan su aplicación económica en un plan bien fundamentado de administratión en el uso de la tierra. La Agènda para el Desarrollo Internationál apoya proyectos que ilustran este sistema. Se sugiere un paradigma para la investigation y el desarrollo permitiendo en estos proyeetos actividades interdisciplinarias que enfoquen el desarrollo de una agricultura sostenible.
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Nature Biotechnology journal featuring biotechnology articles and science research papers of commercial interest in pharmaceutical, medical, and environmental sciences.
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