In the present study, inter- and intrapopulation diversity of five named rice landraces from parts of Odisha state of India representing static and dynamic management was examined using 14 sequence-tagged microsatellite site primer pairs. A total of 64 alleles were detected in ten populations of the five named landraces. The number of alleles ranged from 2 to 7, with an average of 4.57 alleles per locus. Of the 64 alleles, 60 were common and four were rare. Moderate-to-low diversity was observed in the landrace populations, with the number of alleles per population ranging from 16 to 25 and the percentage of polymorphism ranging from 14.29 to 64.29, respectively. The analysis of molecular variance indicated a highest variation of 75.7% among populations within groups (static vs. dynamic). The pairwise estimates of FST revealed very high significant population differentiation, which ranged from 0.68 to 0.89, indicating that the populations share limited genetic diversity among them. However, not many variations were observed in the phenotypes of populations representing static and dynamic management. This shows that adaptations of a population apparently persist over generations, but the underlying genotypes change and new alleles or combinations may arise and increase in frequency at the expense of other alleles that have disappeared. The importance of population biology research for in situ conservation requires both descriptive and hypothesis testing to guide technical improvement and management of landrace populations.

Rice landraces have been developed through artificial selection imposed by farmers during the long-term domestication process. Although the global rice diversity is well characterized, few studies have conducted an in-depth analysis of genetic diversity on a local scale. In India, there are many locally adapted non-Basmati aromatic rice landraces in which the pace of improvement is slow, despite their high economic values. The aromatic and quality rice landraces of Manipur, locally called Chakhao (delicious), are important, considering their high economic and cultural values. To conserve and encourage improvement of these landraces, we collected Chakhao accessions from eight districts of Manipur. The aim of the current study was to investigate the level of genetic diversity and structure of 37 Chakhao landraces based on genotyping with 47 microsatellite markers. The genetic diversity analysis revealed high gene diversity (0.673) within the Chakhao population, with values ranging from 0.303 (Poireiton) to 0.471 (mixed Chakhao). The Chakhao rice accessions could be divided into six subgroups based on genetic structure analyses. The population structure derived from the STRUCTURE analysis largely correlated with the farmers' classification of Chakhao landraces. The results of genetic diversity analyses and the indigenous knowledge of the names and use of Chakhao landraces would facilitate the conservation and utilization of this unique genetic resource.

Faba bean is cultivated worldwide and widely used in Mediterranean countries, Asia and Europe. However, only a few faba bean breeders are active in cultivar development. As a result, a limited number of varieties are available for growers. Plant genetic resources or germplasm are fundamental sources for plant breeding, and the assessment of the genetic diversity among germplasm accessions is useful to facilitate more efficient use of plant genetic resources. A mini-core collection of faba bean germplasm (178 landraces and four cultivars), from diverse geographic regions of Turkey, was assessed for agro-morphological performance and some quality traits. There were substantial variations for the investigated morphological and quality characteristics. The analysis of variance revealed that the differences among 182 accessions were significant for all the studied characters. Some accessions showed very good agronomic performance for some traits. Positive and negative correlations existed among different morphological and agronomic traits. Landraces have been classified into four different groups using a cluster analysis. These results suggest that an a priori classification of accessions according to the growing area does not strictly correspond to phenotypic grouping. From the spatial distribution of landraces, however, it has been possible to identify ‘superior’ accessions of some traits. These findings indicate a number of useful traits in the gene pools and a wide range of phenotypic variation that provides a good source of diversity for use in modern faba bean breeding programmes.

Knowledge about genetic diversity among Brassica napus cultivars developed for many growing regions and their possible use as potential inbred lines for hybrid seed production is limited. We studied the genetic diversity and relationships among B. napus accessions using Sequence Related Amplified Polymorphism (SRAP) markers, which preferentially amplify open reading frames. A total of 60 spring-type B. napus accessions were screened using 20 SRAP primers, which revealed 162 polymorphic fragments with an average of eight markers per primer combination. Genetic similarity estimates ranged from 40 to 100, which indicated sufficient diversity among the accessions. The majority of the accessions were uniquely identified by the markers with the exception of near-isogenic inbred lines. Cluster analysis displayed five major groups. The first major cluster comprised 23 accessions mostly of Australian origin, whereas the second cluster included 13 accessions mostly of Canadian origin. The accessions in the first and second clusters were identified as maintainers of cytoplasmic male sterility. The two restorer lines R-111 and R-101 along with their corresponding backcross progeny constituted the third cluster. Scandinavian cultivars made the fourth separate cluster. One cultivar Salam and its respective inbred line were the most divergent lines. Variations in the number of markers between open-pollinated cultivars and their respective selfed inbred lines were also observed. The clustering pattern mostly supported their respective pedigree and characteristic traits. Genetic diversity in genetically distinct groups in the tested maintainer and restorer lines can be exploited for hybrid development in B. napus.

Olea europaea L. has been cultivated in the Mediterranean region for thousands of years and is of major economic importance. The origin of olive cultivars remains as complex to trace as their identification. Thus, their molecular characterization and discrimination will enable olive germplasm management. In addition, it would be a useful tool for authentication of olive products. High-resolution melting (HRM) analysis, coupled with five microsatellite markers, was integrated to facilitate molecular identification and characterization of main O. europaea cultivars collected from the National Olive Tree Germplasm Collection established in Chania, Greece. The five microsatellite loci used were highly informative and generated a unique melting curve profile for each of the 47 cultivars and for each microsatellite tested. In particular, three microsatellite markers (DCA03, DCA09 and DCA17), which generated 29 HRM profiles, were sufficient to genotype all the olive cultivars studied, highlighting their potential use for cultivar identification. Furthermore, this assay provided a flexible, cost-effective and closed-tube microsatellite genotyping method well suited for molecular characterization of olive cultivars.

The search for disease resistance in wild types is continuing, in order to introduce resistant genes from wild relatives. In this study, we found that the wild melon Cucumis prophetarum was comparably more tolerant to salinity, the damping-off disease caused by the fungus Rhizoctonia solani and the root-knot nematode Meloidogyne incognita. The percentage of wild melon survival was 60% compared to that of the cultivated cucumber Cucumis sativus, which was 15%, when irrigated with NaCl at a concentration of 2500 ppm; and 96% for the wild melon compared with 44% for the cultivated cucumber when irrigated with CaSO4.2H2O at a concentration of 1000 ppm. Wild melon plants were more tolerant to R. solani attack, as only 20% of the plants were infested compared with 100% of infestation observed for the cultivated cucumber. The average number of nematode galls was 250 per plant on the cultivated cucumber when compared with 6.3 per plant on the wild species. Wild melon could be a potential source of resistant or tolerant genes that can be transferable to cultivated cucumbers.

Genetic resources form the basis of the new era of global food security. The food crises in many developing countries, reflected by food riots correlated with food prices, have been termed the Silent Tsunami. Plant genetic resources are clearly essential to food security for the future. Fortunately, genetic resources are generally considered a public good and shared internationally. Wild relatives of crop species and their derivatives represent the reservoir of genetic diversity that will help to meet the food demands of nine billion people by 2050. New technologies from genomics bolster conventional plant breeding for enhancing traits to meet these food demands. Genetic diversity is the lifeblood of traditional and modern plant breeding. The dramatic increase in the number of biotech crops reveals the value of new genetic resources. Genetic resources will provide a gateway to a new era of global food security. Although 7.4 million plant accessions are stored in 1750 germplasm banks around the world, only a small portion of the accessions has been used so far to produce commercial varieties. Our challenge is to find better ways to make more efficient use of gene bank materials for meeting food demands in the future.

Niger harbours a wealth of diversity of Africa's rice (Oryza glaberrima) and its related wild species. We therefore engaged in a collecting mission of rice species across growing regions and agrosystems in Niger. A total of 270 rice accessions were assembled, including 177 Asian rice (O. sativa) cultivars, 67 African rice landraces (O.glaberrima), 25 O. barthii and one O.longistaminata. We found most accessions (80.7%) along the Niger River and its tributary the Dallol Maouri. Many of the accessions, except those belonging to the wild O. barthii initially found around the Lake Chad region, were also collected along the Niger River. Drought, insects, birds, rice yellow mottle virus and bacterial blight were noted as major constraints on rice production. Accession naming by farmers was consistent within regions but seldom across regions. Based on the recorded agro-morphological traits, the germplasm was classified into three clusters: (1) O. longistaminata with floating African landraces and late-maturing floating Asian rice; (2) lowland O.barthii and African landraces; (3) a mixture of irrigated Asian rice with lowland accessions of both cultivated species. The phenotypic variability of the germplasm collection, as measured by the Shannon–Weaver diversity index, was relatively high (H′ = 0.69), with accessions in the irrigated agrosystem being less diverse than those in the traditional agrosystems. There was no significant difference in the magnitude of diversity between the main eco-geographical zones and between the clusters. However, some traits contributing the most to this diversity were different. This study suggested a substantial germplasm exchange between regions in Niger.

To assess the genetic diversity of spinach germplasm, 250 individuals of 50 accessions collected from geographically diverse regions (West Asia, East Asia, Japan, Europe and the USA) were analysed using simple sequence repeat (SSR) markers. A total of 39 polymorphic alleles were identified, with an average of 6.5 alleles per locus for six loci. The overall gene diversity (0.62) in the entire set of individuals suggests that the germplasm has high genetic variability. The West Asian accessions showed the highest gene diversity, with a value of 0.57, followed by the East Asian accessions. These results help confirm the notion that spinach originated from West Asia. Hierarchical analysis of molecular variance revealed significant genetic differentiation among the geographical regions, which accounts for 26% of the total variation detected. Furthermore, pairwise Φst values indicate low genetic differentiation between the East Asian and Japanese germplasm accessions, both of which showed high genetic differentiation from the European accessions. The differentiation between the East Asian and European gene pools may be attributed to the founder effect associated with crop dissemination, as well as to the selection and genetic drift that occurred during the breeding process.

Faba bean (Vicia faba L.) is one of the most important legumes in the world. Little is known about the genetic resources of faba bean in Southern Tunisia. In the present study, genetic diversity within Tunisian faba bean germplasms was investigated using 16 simple sequence repeat markers. In total, 50 alleles were detected. The number of alleles per marker ranged from 2 to 6, with an average of 3. Genetic diversity and polymorphism information content values averaged, respectively, 0.43 (range 0.34–0.51) and 0.36 (range 0.28–0.43). The mean heterozygosity value was 0.27. A model-based structure analysis based on neighbour-joining tree and factorial correspondence analysis revealed the presence of two subpopulations, consistent with the clustering based on genetic distance (GD). The overall Fis value was 0.36, indicating the importance of selfing in these populations. Analysis of molecular variance revealed that the within-population genetic variance component was much higher than the between-population or between-subpopulation variance component. The genetic relationships based on Nei's GD revealed that AGD (Aguadulce) and SAG (Super Aguadulce) and TF1 and TF2 (Tafartassa-Gafsa) were the most closely related populations. Assessment of genetic variation within faba bean populations will be informative for the conservation of germplasms and the implementation of effective breeding programmes in Tunisia.

The re-sequencing of the genomes of wild crop relatives is a rapid method to determine the likely utility of the germplasm in crop improvement. The conservation of genetic resources both in situ and ex situ can be guided by information on the novelty of specific populations at the whole-genome and specific allele levels. The analysis of Australian wild relatives of rice, coffee, Macadamia and Eucalypts is being used to support crop improvement and enhance food and energy security. Rice populations that are novel sources of diversity in the A genome of rice have been characterized at the whole-genome level. This has demonstrated the novelty of these species and will support taxonomic revisions of the Oryza species. Variation in the genomes of plants from diverse environments defines strategies that might be employed to develop climate-resilient crop varieties. Eucalypt sequencing aims to support the selection of species and genotypes for use as new energy crops.

The USA is experiencing a prolific invasion of the wood-boring emerald ash borer, Agrilus planipennis. Native to Asia, this beetle completes its life cycle on ash trees and results in nearly complete mortality of all infested trees. In the present study, we examined the levels of genetic diversity and differentiation among eight populations of Fraxinus pennsylvanica (green ash) using five polymorphic microsatellite loci. Genetic information was used to design guidelines for the establishment of a seed collection sampling strategy to conserve the genetic diversity of ash trees. We found high levels of genetic diversity, as indicated by the allelic richness, both across the populations (16.4 ± 5.18 alleles per locus) and within them (8.03 ± 1.21 alleles per locus). The expected and observed heterozygosity was also high (0.805 ± 0.38 and 0.908 ± 0.04, respectively), and there was moderate genetic differentiation among the populations (FST= 0.083) with members of these eight populations grouped into three distinct clusters. We examined the relationship between the number of individuals sampled and the number of alleles captured in a random sample taken from a population of 10,000 individuals. Only sample sizes of 100 individuals captured most of the alleles (average = 78.74 alleles), but only seven of 50 samples effectively captured all the 82 alleles. Smaller samples did not capture all alleles. A probabilistic model was used to determine an optimal sampling strategy, and it was concluded that a collection of 200 seeds from each of five mother trees would have the highest likelihood of capturing all alleles in a population.

Pearl millet (Pennisetum glaucum (L.) R. Br.) is an important staple cereal cultivated in the arid and semi-arid tropics of Asia and Africa, regions severely affected by malnutrition. Knowledge about the extent of genetic variability and patterns of agro-morphological variation in local germplasm from a target region is an important prerequisite for efficient crop improvement. To assess the potential of Sudanese pearl millet landraces as sources of desirable traits for pearl millet improvement including biofortification, a total of 225 accessions were evaluated in Sudan at three locations for agro-morphological traits and at one location for grain mineral nutrient contents (Fe, Zn, Ca, P, K, Mg, Mn, S, Na, Cu and β-carotene). Genetic variation was highly significant, but relatively limited for some agro-morphological traits (62–78 d to flowering, 119–188 cm plant height and 16–34 cm panicle length), pointing to the potential usefulness of a targeted diversification for these traits. Self-pollinated grain micronutrient contents showed a wide variation: 19.7–86.4 mg/kg for Fe and 13.5–82.4 mg/kg for Zn. Significant and positive correlations among most of the nutritional traits were observed; therefore, enhancement of the concentrations of some nutrients will lead to the improvement of other related nutrients. No significant associations were observed between the nutritional and agro-morphological traits, indicating good prospects for simultaneous improvement of both trait categories. No clear patterns of geographic differentiation for specific traits were detected for the Sudanese pearl millet. Nutrient-rich accessions were identified and those with acceptable agro-morphological traits are encouraging materials for future pearl millet biofortification programmes in Sudan.

The overexpression of wheat Bx7 subunit (Bx7OE) encoded by the Glu-B1al allele is originated from a duplication event of the Bx7 gene, and has a positive effect on gluten strength. Thus, it is an important genetic resource for wheat quality improvement. In this study, the Bx7OE subunit from a large number of bread wheat and related species was characterized by sodium dodecyl sulphate–polyacrylamide gel electrophoresis, reversed-phase high-performance liquid chromatography (RP-HPLC) and Sequence-Tagged sites (STS) markers. Only 31 bread wheat varieties were found to carry Bx7OE. RP-HPLC quantification analysis revealed that the mean proportion of the Bx7OE subunit to the total amount of high-molecular-weight glutenin subunits among the 31 bread wheat varieties was 41.8%, which is much higher than that of varieties with the normal Bx7 subunit (generally at 30%). Flour quality analysis of seven representative varieties with Bx7OE and three with the normal Bx7 subunit showed that the varieties with Bx7OE generally displayed better gluten strength than those with the normal Bx7 subunit. STS markers demonstrated that, in addition to the 31 bread wheat varieties with Bx7OE, no PCR products were obtained from the related Triticum and Aegilops species. This suggests that the retroelement-mediated recombination event at the Glu-B1 locus could have occurred more recently, later than the formation of hexaploid wheat. The Bx7OE subunit is mainly distributed in some bread wheat varieties from American countries with a low frequency, which is of particular importance for the quality improvement of wheat gluten.