Mungbean yellow mosaic virus (MYMV) is a disastrous pathogen of mungbean. It is widespread in most of southern India and no complete resistance has been identified among its commercial cultivars. Two isolates of MYMV, representing its diversity, were used to assess and characterize the susceptibility reaction of all the three species of Vigna. The seeds were agroinoculated with the virus and the presence of the viral DNA was confirmed after 12 d by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis after which the plants were monitored for the expression of symptoms. All of the 20 accessions of Vigna radiata and ten accessions of Vigna mungo were systemically infected with MYMV, and they all produced typical symptoms. On the other hand, the 24 accessions of Vigna umbellata were found to be resistant to both the isolates. For additional affirmation, three representative accessions of V. radiata and V. mungo and all the accessions of V. umbellata were agroinoculated, and quantitative RT-PCR was performed for the quantitative detection of the MYMV. The mRNA transcripts of MYMV were detected in V. radiata and V. mungo plants but not in the V. umbellata plants. Researching the molecular basis of the resistance in V. umbellate against MYMV might definitely be very constructive for developing resistant varieties of mungbean on a commercial scale. This genetic quality offering resistance to MYMV could also be incorporated into V. radiata/V. mungo by means of interspecific crosses.

Niche modelling software can be used to assess the probability of detecting a population of a plant species at a certain location. In this study, we used the distribution of the wild relatives of lettuce (Lactuca spp.) to investigate the applicability of Maxent species distribution models for collecting missions. Geographic origin data of genebank and herbarium specimens and climatic data of the origin locations were used as input. For Lactuca saligna, we varied the input data by omitting the specimens from different parts of the known distribution area to assess the robustness of the predicted distributions. Furthermore, we examined the accuracy of the modelling by comparing the predicted probabilities of population presence against recent expedition data for the endemic Lactuca georgica and the cosmopolitan Lactuca serriola. We found Maxent to be quite robust in its predictions, although its usefulness was higher for endemic taxa than for more widespread species. The exclusion of occurrence data from the perceived range margins of the species can result in important information about local adaptation to distinct climatic conditions. We discuss the potential for enhanced use of Maxent in germplasm collecting planning.

The primary mission of germplasm collections is to preserve genetic diversity, but germplasm is preserved so that it can be used. Historically, the standard practice is that all germplasm accessions should be maintained as collected, so that even self-pollinated accessions are maintained as heterogeneous seed lots. In theory, this seems like an ideal strategy for preserving genetic diversity, but in practice, it is simply not workable. Heterogeneous accessions are in constant risk of change and loss. It is possible to mitigate the risk factors, but they can only be lessened and not eliminated. Maintaining pure-lined accessions for self-pollinated species not only eliminates the problems associated with genetic drift and natural selection, but also enhances the accuracy of the evaluations and fosters effective germplasm utilization. Neither the current potential to characterize entire germplasm collections with tens of thousands of DNA markers nor the future potential of whole genome sequencing to completely characterize the diversity of all accessions in collections can be fully realized for self-pollinated species unless accessions are homogeneous and homozygous. In this manuscript, the case is made for pure-lining self-pollinated germplasm accessions using the USDA Soybean Germplasm Collection, which has maintained pure-lined accessions for over 50 years, as an example. There is also an analysis of the extensive seed distribution from this collection to indicate the value of a diverse collection of genotypes.

The water lotus, genus Nelumbo, contains two species, the sacred (Nelumbo nucifera) and American lotuses (Nelumbo lutea). Hundreds of flowering lotus cultivars are currently known. However, their classification is unclear. For the classification of Nelumbo cultivars, in addition to 35 simple sequence repeat (SSR) markers recently developed, we have developed 17 and 16 of new Nelumbo SSR markers from SSR-enriched genomic libraries and expressed sequence tag (EST) data, respectively. Out of these 68 SSRs, along with SSRs recently published by others, 52 showed clear polymorphisms in 98 Nelumbo samples. A total of 300 alleles were observed, ranging from 2 to 11 alleles per locus, with an average of 5.77. Alleles specific for the American lotus-derived cultivars and a cluster of the American lotus-derived cultivars on a neighbour-joining tree confirmed genetic differences between N. lutea and N. nucifera. In addition, a possible differentiation between Chinese and Japanese cultivars was also suggested. Parentage analysis using the SSR markers confirmed four known parentages and predicted currently-unknown parentages of six cultivars. The present data have demonstrated that site-specific, co-dominant SSR markers enable more accurate classification, identification and comparison of Nelumbo species.

African yam bean, AYB (Sphenostylis stenocarpa Hochst. ex. A. Rich Harms), is a tuberous legume of tropical Africa. AYB has the potential to significantly boost food security due to its considerable nutritional qualities. However, the crop is underutilized. To efficiently utilize AYB genetic resources for its improvement, it is necessary to understand the crop's diversity. This study investigated the amplification ability of 36 cowpea simple sequence repeat (SSR) primers across AYB genomic DNA, extracted from 67 accessions. Thirteen (36%) of the cowpea SSRs showed transferability in AYB. Eight of these SSRs amplified above 60% of AYB accessions and generated 55 polymorphic fragments with an average of 6.9 per primer. Polymorphic information content ranged from 0.6691 to 0.8857 with an average of 0.7791. This study also assessed the genetic diversity within 67 AYB accessions using eight cowpea (Vigna unguiculata L. Walp)-derived SSR primers. The result revealed a high level of genetic diversity with simple matching coefficient ranging from 0.458 to 1.000. A dendrogram depicting three main clusters was generated based on unweighted pair group method with arithmetic average. Cluster 1 was the most diverse with a dissimilarity range of 0.517–1.000. The level of genetic diversity revealed in this study indicates that the studied AYB germplasm can be exploited for genetic improvement. Additionally, the transferable markers will aid AYB genome research and also make possible the comparative mapping between AYB and cowpea.

To investigate the genetic diversity and structure of Jatropha curcas L. oilseed plant, in this study, native populations from Chiapas, Mexico, were evaluated, using microsatellite DNA markers. A total of 93 representative samples were selected from seven sites in two regions in the state of Chiapas grouped by geographical proximity, where leaf samples were collected to isolate the genomic DNA. Individual polymerase chain reactions were carried out with ten pairs of specific oligonucleotides for the microsatellites of J. curcas, separating the products of amplification by acrylamide electrophoresis. Twenty-seven fragments were detected (77% polymorphic) with which heterozygous individuals were distinguished. The most informative microsatellite was Jcps20 (nine alleles, polymorphic index content 0.354). The average polymorphism per population was 58%. The Hardy–Weinberg tests revealed a reproductive pattern of non-random mating. The diversity descriptors and the analysis of molecular variance revealed that the populations were structured and moderately differentiated (FST 0.087) and that this differentiation was not due to isolation by distance, as the Mantel test was not significant (P= 0.137), but rather due to allopatry. Bayesian analysis revealed that the accessions belonged to only four genetic groups and confirmed the differentiation between the regions. Because some loci were in Hardy–Weinberg disequilibrium, it is proposed that differentiation is due to the clonal reproduction of J. curcas practised by farmers in Chiapas, along with the anthropogenic dispersion at regional levels. The results of this study reveal that J. curcas in Chiapas has genetic diversity that is greater than that reported in other parts of the world, which represents a potential germplasm pool for the selection of genotypes.

Variety registration is an important area of plant genetic resource characterization and utilization. Within the European Union, varieties must be included on a National List (NL) of a member state or on the Common Catalogue (a compilation of the NLs of the member states) before seed can be sold. This requires a series of tests and trials which assess if the variety is distinct, uniform and stable (DUS) and if it has sufficient value for cultivation and use (VCU). The same DUS criteria are also used world-wide for the granting of Plant Breeders' Rights (PBR), an intellectual property protection system. Both DUS and VCU are currently assessed primarily using field-based trials. However, the potential use of biochemical and molecular markers for DUS purposes is being actively investigated and such markers could have an important role to play in maintaining the quality and scope of PBR in an environment where the increasing number of countries involved in DUS testing and the number of variety comparisons to be made are causing logistical difficulties. More recently, given firstly the increase in the availability of markers from expressed regions of the genome, and secondly the possibilities raised by detailed DNA sequencing programmes and the association of markers (particularly single nucleotide polymorphisms, SNPs) with specific genes, the prospects for a more molecular approach to VCU are also being discussed. This paper reviews the current situation with regard to the use of molecular markers for DUS and VCU testing and considers future prospects for variety registration in the 21st century, ‘-omics’, era.

A regional (Oceania) core collection for taro germplasm has been developed based on phenotypic and molecular characterization. In total, 2199 accessions of taro germplasm have been collected by TaroGen (Taro Genetic Resources: Conservation and Utilisation) from 10 countries in Oceania: Papua New Guinea, Solomon Islands, Vanuatu, New Caledonia, Fiji, Palau, Niue, Tonga, Cook Islands and Samoa. Our objective was to select 10% from each country to contribute to a regional core. The larger collections from Papua New Guinea, Vanuatu and New Caledonia were analysed based on phenotypic characters, and a diverse subset representing 20% of these collections was fingerprinted. A diverse 20% subsample was also taken from the Solomon Islands. All accessions from the other six countries were fingerprinted. In total, 515 accessions were genotyped (23.4% overall) using taro specific simple sequence repeat (SSR) markers. DNA fingerprint data showed that great allelic diversity existed in Papua New Guinea and the Solomon Islands. Interestingly, rare alleles were identified in taros from the Solomon Islands province of Choiseul which were not observed in any of the other collections. Overall, 211 accessions were recommended for inclusion in the final regional core collection based on the phenotypic and molecular characterization.

Chlorophytum borivilianum is an important medicinal plant known as ‘Safed musli’, used in many Ayurvedic vital tonics and aphrodisiac formulations. The species was first described from India in 1954 and reached rare status in nature due to overexploitation. Owing to its increased demand, the species has attracted the attention of farmers as well as researchers in several institutions. The present paper deals with various research aspects such as conservation biology, cytology, chemistry, plant genetic resources, micropropagation, crop management, etc. conducted on the crop for the last two decades in India. The species is diploid 2n=4x=28 and is mainly vegetatively propagated. Seeds remain dormant for nearly 10 months and also suffer from poor germination. Fleshy roots of the species contain saponins having therapeutic value. Germplasm collections made from different states in India show the occurrence of wide genetic variability in terms of plant type, maturity period, growth and yield characters, and size and shape of fleshy roots. Although the species is cross-pollinated in nature, self-pollination is also feasible artificially. One high-yielding cultivar and two high-yielding morphotypes have been recently identified. A micropropagation protocol using different explants has been standardized and agrotechnology for cultivation developed. Successful use of synthetic seed has also been reported. The article presents a comprehensive overview of the current state of research in the species with due emphasis on future thrust and possibilities.

Seventeen populations of niger (Guizotia abyssinica), representing all regions in Ethiopia where this crop is grown, were investigated using the amplified fragment length polymorphism (AFLP) technique, in order to determine the extent and distribution of its genetic diversity. A total of 539 AFLP loci were scored using seven primer combinations applied to 170 individual plants. Of these, 90% were polymorphic and all the individuals investigated were genetically unique. Despite the fact that most of the variation was within populations, populations were differentiated at a significant level (analysis of molecular variance; P < 0.001). There were no significant differences between populations in relation to the extent and altitude of cultivation. A significant positive correlation was revealed between Nei's standard genetic distance and geographic distance. Cluster analysis and principal coordinate analysis revealed that populations from the same regions were clustered together in most cases. Further collection of niger germplasm from areas underrepresented in gene bank collections is recommended.

This paper shows the results of the investigation on some ecological aspects and on the sanitary status of the wild Euroasiatic native grapevine (Vitis vinifera L. ssp. sylvestris (Gmelin) Hegi) in Georgia (South Caucasus). This taxon is seriously endangered by human activities such as forest cleaning and setting fires. Moreover, invasive Vitaceae of the North American origin, imported after phylloxera (Daktulosphaira vitifoliae Fitch) when vineyards were being replanted, increase the risk to lose these spontaneous vines. The survey includes collection of data on the population structure, the plant sex ratio, the main botanical supporters of the vines and the associated flora, the presence of invasive vines of the North American origin and the incidence of phytophagous arthropods and pathogens. The phytosanitary study showed that monophagous eriophyid mites and exotic fungal diseases, such as downy (Plasmopara viticola (Berkeley and Curtis) Berlease and de Toni) and powdery mildews (Erysiphe necator –(Schweinitz) Burrill), cause symptoms on all the observed populations. The absence of symptoms caused by phylloxera, root-knot nematodes and root rot is remarkable. However, the level of detected injuries caused by these parasitic organisms does not seem to be a real problem for the survival of the populations.

The allelic diversity within oil palm populations (45 native ones from 10 African countries, three breeding populations and one collection of semi-wild material) was determined using 16 microsatellite markers. A total of 209 alleles were detected, with a mean number of 13.1 alleles per locus. The mean effective number of alleles per locus (Ae) was 3.3 ± 1.3. Although the Duncan's multiple range test only separated the group of populations from Madagascar from the rest on the basis of Ae, the presence of unique and rare alleles and high values of Ae suggest that 23 of the African populations should be conserved to secure allelic diversity.

We analysed the patterns of variation for 14 qualitative and 12 quantitative traits in 11,402 pigeonpea germplasm accessions from 54 countries, which were grouped into 11 regions. Semi-spreading growth habit, green stem colour, indeterminate flowering pattern and yellow flower colour were predominant among qualitative traits. Primary seed colour had maximum variability and orange colour followed by cream were the two most frequent seed colours in the collection. Variances for all the traits were heterogeneous among regions. The germplasm accessions from Oceania were conspicuous by short growth duration, short height, fewer branches, pods with fewer seeds, smaller seed size and lower seed yields. The accessions from Africa were of longer duration, taller, with multi-seeded pods and larger seeds. The germplasm diversity indicated by Shannon–Weaver diversity index (H′) pooled over all traits, was highest for Africa (0.464±0.039) and lowest for Oceania (0.337±0.037). The cluster analysis based on three principal component scores using 12 quantitative traits revealed formation of three clusters: cluster 1 includes accessions from Oceania; cluster 2 from India and adjacent countries; and cluster 3 from Indonesia, Thailand, the Philippines, Europe, Africa, America and the Caribbean countries. Pigeonpea-rich countries such as Myanmar, Uganda, and others like Bahamas, Burundi, Comoros, Haiti and Panama are not adequately represented in the collection, and need priority attention for germplasm exploration.

To evaluate the responses of some important agronomic traits of 14 bread wheat cultivars, a split plot experiment was conducted based on a randomized complete block design under non-stress, moderate and severe salinity stress conditions. In this study, Backcross and Roshan were identified as the most salinity-tolerant cultivars, while Mihan and Shirudi were considered as the most salinity-sensitive cultivars. The proline content, as well as Δ1-pyrroline-5-carboxylate synthase (P5CS) and vacuolar-type H+-ATPase subunit E (W36) gene expression levels, were examined in these cultivars under normal, moderate and high salinity stress conditions. The proline content and P5CS gene expression level increased with a rise in NaCl concentration. Further, a direct relationship was observed between the proline content and P5CS gene expression in all samples. Our results showed that W36 gene expression in Backcross and Roshan cultivars, as the most resistant ones, strongly increased with elevation of the NaCl concentrations. On the other hand, in the sensitive cultivars such as Mihan and Shirudi, small changes were observed in the gene expression levels with rising salinity levels. Additionally, Backcross and Roshan cultivars had the highest proline content as well as P5CS and W36 genes expression levels under moderate and high salinity stress levels.

In this paper, Shannon–Weaver diversity indices were employed to examine the phenotypic diversity in 271 Ethiopian tetraploid wheat accessions in relation to characters, regions of origin and altitude. Moreover, review of genetic diversity studies in Ethiopian tetraploid wheat was made to explore breeding opportunities. The diversity index varied widely across regions. Among the four altitudinal classes, the highest (0.72) and lowest (0.61) mean diversity indices were observed in altitude classes II and IV, respectively. The diversity index (H′) showed that most traits are polymorphic. The partitioning of the total phenotypic diversity into within- and among-region diversity indicated that 71% of the total variation was attributed to the within-region diversity. Principal component analysis was computed to examine the regional and altitudinal patterns of variation. On regional bases, the first four axes, whose eigenvalues are greater than 1, explained about 82% of the observed phenotypic diversity in the 271 tetraploid wheat accessions. On altitudinal bases, however, only the first two principal components explained 89.7% of the total variation. In general, phenotypic diversity showed considerable differences for each trait in different geographical regions and altitudinal classes which could be utilized in wheat improvement programmes. Breeding opportunities and strategies are suggested.

The antimalarial drug artemisinin (ART) is commercially extracted from the medicinal plant Artemisia annua L. Here, we report the screening of 70 A. annua plants representing 14 diverse germplasm accessions sourced from around the world, and identify lines containing >2% ART. These extremely high-yielding individuals have been maintained as vegetative clones, and they represent promising germplasm resources for future A. annua breeding programmes.

Production of summer squash, Cucurbita pepo, can be severely limited by viral pathogens and powdery mildew. Resistance has been introgressed from Cucurbita moschata, and resistant hybrids have been commercially deployed. Our objective was to assess genetic affinities of such hybrids with susceptible, open-pollinated cocozelle and zucchini cultivars, and two disease-resistant lines derived from six generations of backcrossing to a susceptible zucchini cultivar. Amplified fragment length polymorphism (AFLP) EcoRI/MseI primer combinations were employed and, based on the resulting polymorphic bands, genetic similarities were estimated, and an unweighted pair group method using arithmetic average (UPGMA) cluster analysis was conducted. The open-pollinated cocozelle cultivars clustered with the resistant hybrids. The hybrids had greater similarities with one another than did the open-pollinated cultivars. The zucchini cultivars and their resistant backcross lines formed their own exclusive cluster. However, the resistant backcross lines showed less than 0.80 similarity with their recurrent parent. As the chromosome number of Cucurbita is high (2n = 2x = 40) and the resistances are inherited monogenically and oligogenically, these results, after six generations of backcrossing, cannot be explained by classical genetic linkage.

The regions of north-eastern Ethiopia are known for their high levels of sorghum genetic diversity, and for being drought prone. For centuries, sorghum has been developed and maintained by farmers for its adaptation to the marginal and heterogeneous environment of these regions. The objective of this study was to examine the genetic diversity and population structure of 200 sorghum landraces collected from seven lowland districts, using 30 microsatellite markers sampled from all linkage groups of the sorghum genome. Both distance-based and model-based analytical approaches were used to analyse the data. The data analysis revealed that there was a large variation among all the markers under study. The values of polymorphic information content ranged from 0.26 to 0.88, with a mean value of 0.61, reflecting the high discriminating ability of the markers studied. The mean value of total gene diversity was 0.69, which partitioned 86% among the landraces and 14% within the landraces. Gene diversity among the landraces was largely due to the variation among the genotypes within the geographic origins. Landraces sampled from different collection sites appeared to cluster together, indicating the existence of a high level of gene flow among the sites of collection. This indicates that a relatively small, random collection of landraces would capture the bulk of genetic diversity in the target area. A moderately high level of genetic differentiation and a relatively low level of gene flow were observed between sorghum races and maturity groups. Given that the target area is marginal, drought prone and heterogeneous, the study of genetic diversity among sorghum landraces could serve as an important indicator of valuable alleles for drought tolerance in future sorghum improvement programmes.

Successful conservation strategies require that taxa are prioritized because resources for planning and implementation are always limited. In this study, we created a partial checklist of crop wild relatives (CWR) that occur in the Southern African Development Community (SADC) region and identified the taxa of highest priority for regional conservation planning based on their importance for food and economic security. We found that the region contains over 1900 wild relatives of species cultivated for food, beverages, ornamental, forage/fodder, forestry, medicinal, environmental and other uses. Prioritization of these species was based on two criteria: (i) the value of the related crop for human food and economic security in the region and/or globally, and (ii) the potential or known value of the wild relatives of those crops for crop improvement. The region contains 745 CWR species related to 64 human food and beverage crops that are of high socioeconomic importance and 100 of these are of immediate priority for conservation action. The results of this study show that the SADC region contains a wealth of CWR diversity that is not only of value for food and economic security within the region but also globally. Furthermore, this study represents the first step in developing a CWR conservation and sustainable use strategy for the region, where its implementation would contribute to food security and well-being.

In order to describe the phenotypic diversity in a core collection of grasspea, 47 progenies of single plants (pure lines) selected from 25 accessions were evaluated. Sixteen morpho-agronomic characters including seed 3-(β-N-oxalyl)-l-2,3 diaminopropionic acid (β-ODAP) content were studied. Univariate and multivariate analyses (principal component analysis and cluster analysis) were performed to estimate differences between progenies. Some high-yielding lines could be used directly for cultivation as new varieties and/or as parental lines in crossing programmes. Seed β-ODAP concentration varied from 0.24% to 0.64%. However, a medium to high seed β-ODAP level was recorded for most of the lines, and no significant correlation was observed between this and other morphological traits.