Yellow mosaic disease (YMD) caused by mungbean yellow mosaic virus (MYMV) is one of the most destructive biotic production constraints in mungbean. Development and introduction of resistant cultivars are considered as the most economical and eco-friendly option to manage YMD, for which availability of stable sources of resistance is a pre-requisite. A set of 14 mungbean genotypes including a susceptible check were evaluated for responses to YMD under natural infection across three seasons and under challenged inoculation in glasshouse for one season. None of the genotypes were immune to YMD and produced different degrees of response to MYMV in terms of yellow mosaic symptoms (YMS). Based on the delayed appearance of initial YMS, and lower estimates of per cent disease index and area under disease progressive curve (AUDPC) in response to natural infection and challenged inoculation, five genotypes namely AVMU 1698, AVMU 1699, AVMU 16100, AVMU 16101 and KPS 2 were identified as resistant to YMD. Failure of detection of MYMV through polymerase chain reaction (PCR) using MYMV coat protein gene-specific primer and successful detection of the same through rolling circle amplification-PCR suggested latent infection of MYMV in resistant genotypes. The resistance response of the five genotypes could be attributed to enhanced activities of enzymes such as peroxidase, polyphenol oxidase and phenylalanine ammonia lyase and increased concentration of total phenols. These results are discussed in relation to strategies to breed mungbean for resistance to YMD.

Soil phosphorus (P) deficiency is one of the major challenges for the cultivation of rice worldwide because it limits the growth and productivity of the crop. Therefore, the ability to grow in P-deficit soils is an important trait for rice cultivation. O . rufipogon Griff., a wild relative of rice, is a source of genetic variation for low phosphorus tolerance. The present study was undertaken to identify low P stress-tolerant introgression lines by analysing stress tolerance indices of 40 introgression lines of O. rufipogon. The populations were screened under low soil P and normal soil P plots for two growing seasons. Based on yield under stress and normal conditions, we computed different stress indices, including stress tolerance index (STI), tolerance index, yield reduction ratio (YR), stress susceptibility index, yield stability index (YSI), yield index, per cent yield reduction and geometric mean productivity (GMP). The studies of correlation analysis, principal component analysis and clustering revealed that STI, YSI and GMP were ideal indices for the selection of genotypes that performed well under both stress and normal conditions. Based on these indices, introgression lines (IL-24, IL-29 and IL-32) were identified as promising low P tolerant lines, which exhibited better grain yield under both stress (YS) and normal (YP) conditions. These pre-breeding lines serve as valuable genetic resources for low P tolerance in rice breeding programmes across the world.

Barnyard millet accessions (257) were inoculated with grain smut spores at anthesis stage during 2003. Seed produced on inoculated ear heads was sown in 2005 and resulting plants evaluated for ten morphological traits and grain smut incidence. The accessions were grouped into seven groups based on origin. The lowest mean grain smut incidence was recorded for advance breeding lines, while highest mean value was observed for Uttarakhand group. Genes determining grain yield and susceptibility to grain smut were at most loosely linked as evidenced by non-significant correlations between grain smut incidence and grain yield in six out of seven groups as well as whole collection. Smut resistance along with grain yield in barnyard millet can be enhanced by adopting proper breeding strategy; therefore, in segregating generations, selection should be carried out for both characters simultaneously.

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.

Data on intra-specific variability for seed oil content, physical characteristics and fatty acid composition in Cucurbita moschata and Cucurbita argyrosperma are lacking in the scientific literature. We examined 528 genebank accessions of C. moschata and 166 accessions of C. argyrosperma – which included members of both subsp. argyrosperma and subsp. sororia – for seed oil content, oil physical characteristics and fatty acid composition. The oil of both species had near-identical viscosities, viscosity indices, colour and oxidative stabilities while the oil of C. argyrosperma had a slightly higher pour point, cloud point, percentage of free fatty acids and acid value when compared with C. moschata. Mean oil content values of the two species were similar at 28.7 ± /2.7 and 29.8 ± /2.6% for C. moschata and C. argyrosperma, respectively. The mean seed oil content of C. argyrosperma subsp. argyrosperma var. palmeri (32.1%) was significantly higher than that of the other taxa examined. The average (mean) percentage of total seed weight attributable to the kernel was 77.2% in C. moschata (n= 34) and 74.5% in C. argyrosperma (n= 46). The percentage of total seed weight attributable to the hull was correlated with seed oil content, in both species. Linoleic was the predominant fatty acid in all the samples analysed. Means for individual fatty acids in C. moschata were linoleic 48.5%, oleic 22.6%, palmitic 20.7% and stearic 7.5%. Means for individual fatty acids in C. argyrosperma were linoleic 47.3%, oleic 27.5%, palmitic 16.5% and stearic 8.0%.

The grain morphology of 17 wild rice relatives were studied by light and scanning electron microscopy and compared to two cultivated rice varieties (Oryza sativa cv. Nipponbare and O. sativa cv. Teqing). Observations were made of the grain colour, size and shape. Grains from wild rice species exhibited a variety of colours that have potential aesthetic and nutritional value. The grains of these species exhibited a wide array of sizes and shapes, but still fell within the standard classification scale that rice breeders use for routine breeding evaluation. These results highlight the potential of these species as whole grain foods or as sources of novel alleles in conventional rice breeding programmes.

This study is the first assessment of the entire soybean [Glycine max (L.) Merr] collection of the United State Department of Agriculture National Plant Germplasm System (USDA) reporting quantitative and population genomic parameters. It also provides a new insight into soybean germplasm structure. Germplasm studies enable plant breeders to incorporate novel genetic resources into breeding pipelines to improve valuable agronomic traits. We conducted comprehensive analyses on the 19,652 soybean accessions in the USDA-ARS germplasm collection, genotyped with the SoySNP50 K iSelect BeadChip SNP array, to elucidate the quantitative properties of existing subpopulations inferred through hierarchical clustering performed with Ward's D agglomeration method and Nei's standard genetic distance. We found the effective population size to be approximately 106 individuals based on the linkage disequilibrium of unlinked loci. The cladogram indicated the existence of eight major clusters. Each cluster displays particular properties with regard to major quantitative traits. Among those, cluster 3 represents the tropical and semi-tropical genetic material, cluster 5 displays large seeds and may represent food-grade germplasm, and cluster 7 represents the undomesticated material in the germplasm collection. The average FST among clusters was 0.22 and a total of 914 SNPs were exclusive to specific clusters. Our classification and characterization of the germplasm collection into major clusters provides valuable information about the genetic resources available to soybean breeders and researchers.

Crop wild relatives (CWR) are wild plant taxa relatively closely related to crops that can contribute beneficial traits for crop improvement, such as biotic and abiotic stress resistance. Turkey has a rich flora of approximately 11,000 higher plant taxa, has two Vavilov centres of crop diversity (i.e. the Mediterranean and the Near East), is recognized as the cradle of agriculture providing the northern boundary of the Fertile Crescent, and has recently been identified as the country with the highest concentration of CWR diversity. The objective of this paper is to present the results of a gap analysis of CWR genetic diversity in Turkey using existing data sources of 458 of the 764 priority CWR taxa with available georeferenced data. In total, 27,597 presence points were obtained from the Global Biodiversity Information Facility, Aegean Agricultural Research Institute in Menemen and Field Crops Central Research Institute, Ankara. Geographic Information System (GIS) software was used to identify taxon richness, sampling bias, future ex situ population collection and location where existing protected sites could form the basis of national network of in situ genetic reserves. CWR taxon richness was located along the Aegean Coast, Syrian border and southern Mediterranean coast. Current ex situ representation of CWR taxa is inadequate and further collection across the entire country is required. The highest priority in situ reserve location is found in Izmir, Sanliurfa and Antalya province, which reflects overall CWR richness.

Crop wild relatives (CWRs) play a key role in crop breeding by providing beneficial trait characteristics for improvement of related crops. CWRs are more efficiently used in breeding if the plant material is genetically characterized, but the diversity in CWR genetic resources has often poorly been assessed. Seven seed collections of Musa balbisiana, an important CWR of dessert and cooking bananas, originating from three natural populations, two feral populations and two ex situ field collections were retrieved and their genetic diversity was quantified using 18 microsatellite markers to select core subsets that conserve the maximum genetic diversity. The highest genetic diversity was observed in the seed collections from natural populations of Yunnan, a region that is part of M. balbisiana's centre of origin. The seeds from the ex situ field collections were less genetically diverse, but contained unique variation with regards to the diversity in all seed collections. Seeds from feral populations displayed low genetic diversity. Core subsets that maximized genetic distance incorporated almost no seeds from the ex situ field collections. In contrast, core subsets that maximized allelic richness contained seeds from the ex situ field collections. We recommend the conservation and additional collection of seeds from natural populations, preferentially originating from the species' region of origin, and from multiple individuals in one population. We also suggest that the number of seeds used for ex situ seed bank regeneration must be much higher for the seed collections from natural populations.

In this study, the genetic constitution of wild grape populations distributed in the Zagros Mountains in the north-west part of Iran was investigated to assess their risk of extinction and to identify the most suitable conservation strategy. A total of 65 wild grapevine samples from five different populations were analysed using 23 SSR loci. Consistent allelic richness was detected in all the analysed populations (from 4.01 to 5.35). The observed heterozygosity and expected heterozygosity were high with mean values of 0.67 and 0.69, respectively. A modest heterozygosity deficiency was detected only in the Piranshahr and Sardasht-Shalmash populations. The neighbour-joining dendrogram clustered the accessions into three groups corresponding to the geographical distribution of the populations. Molecular data combined with field evaluation revealed that an ex situ conservation approach is the most suitable strategy for preserving the genetic richness of Iranian wild grape populations with consistent rare alleles (about 20%). We propose in situ preservation only in the case of the Sardasht-Ghasmarash population to ensure that evolutionary dynamic forces continue to influence plant adaptation and survival in response to environmental alterations.

Population structure and linkage disequilibrium (LD) were investigated in a set of 395 bread wheat landraces including 154 spring, 193 winter, two facultative wheat and 46 unknown growth type collected from different geographical regions of Iran. A total of 53 microsatellite markers distributed in three genomes of wheat were assayed for polymorphism. The 312 polymorphic alleles were served to estimate population structure and analyse the genome-wide LD. The number of alleles ranged from 2 to 18 with an average of 5.89 alleles/locus. Mean of polymorphic information content was 0.6 with a range of 0.15–0.86 and gene diversity varied from 0.16 to 0.88 with an average of 0.64. The population of landraces was highly structured and based on distance-and model-based cluster analyses the 395 landraces were assigned into eight subpopulations: SG1–SG8. Population structure estimates based on simple sequence repeat (SSR) marker data were quantified in a Q matrix and used in calculation of LD between pair of markers. A low overall LD level found in 12–13% (166) of the SSR marker pairs showed significant pairwise LD in r2 ≥ 0.01 and P ≤ 0.001 and six pair showed r2 ≥ 0.05 with P ≤ 0.001. LD clearly decays within the genetic distance of 40–60 cM with r2 ~ 0.05. The results of this study should provide valuable information for future association mapping using this wheat collection.

In Ethiopia, barley is used to make various types of foods, and home-made and industrial beverages. The various kinds of end-use of barley grain by rural people in two districts of West Shewa are reported. According to farmers, no other cereal crop can be processed into so many different forms of food. At least 17 kinds of foods and beverages, which are consumed in the form of whole-grain snacks, sauces, soups, drinks and baked foods, were reported. Some are mainly served on special occasions like annual ceremonies and cultural gatherings, while others are served as main dishes. Black- and purple-grained barleys are preferred for malting and home-made alcoholic drinks, whereas white-grained types are used for baking and roasting. Each landrace has its own inherent property that makes it suitable for at least one end-use. Since ancient times, barley foods are also known to farmers as remedies and traditional medicines for many kinds of diseases. The various kinds of utilizations of barley and its value in the socio-cultural lifestyles of farmers play vital roles for the on-farm maintenance of different landraces in West Shewa.

The International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) genebank in India holds the world's largest collection of 21,594 pearl millet germplasm accessions including 18,447 landraces from 50 countries. West and Central Africa (WCA) region, which is considered as the centre of diversity for pearl millet, is also an important pearl millet germplasm source for resistance to biotic and abiotic stresses. A total of 7372 landraces were assembled from WCA countries. Out of which, 6434 landraces have the georeference data. The geographic origins of these landraces were analyzed using geographic information system tools to identify gaps in the collection. Geographical distribution of existing collections, type of vegetation, land cover and the high probability (>70%) for the occurrence of pearl millet estimated using the FloraMap software in different countries show that 62 districts in 13 provinces of Nigeria, 50 districts in 16 provinces of Burkina Faso, 9 districts in 6 provinces each of Mali and Mauritania, 8 districts in 8 provinces of Chad and 7 districts in 3 provinces of Ghana as the major geographical gaps in the pearl millet collection at the ICRISAT genebank. In view of this, we suggest that the final areas for exploration in these districts should be decided prior to the launch of the collection missions in consultation with local government officials and extension officers, who have the knowledge of pearl millet cultivation in the districts identified.

DNA methylation is known to regulate gene expression when plants are exposed to abiotic stress such as drought. Therefore, insight into DNA methylation pattern would be useful for a better understanding of the expression profile of genes associated with drought adaptation. In the present study, we attempted to analyse the DNA methylation pattern at the whole-genome level and the expression of a few drought-responsive genes in rice under different regimes of soil water status, i.e. puddled, 100 and 60% field capacities (FC). The methylation-sensitive randomly amplified polymorphic DNA analysis was employed to identify DNA methylation pattern. We observed an increase in DNA methylation at 60% FC, and reduced methylation under 100% FC compared to puddled condition. The genes such as protein phosphatases (PP2C) and phenylalanine ammonia-lyase (PAL) having CpG islands in their promoter region had lower expression level under 100 and 60% FC compared to puddled conditions. Heat shock protein 70 (HSP70) and RNA helicase 25 (RH25), with no CpG islands in their promoter region, exhibited enhanced expression compared to puddled plants. In rice, increased DNA methylation seems to be an important mechanism associated with drought responses, which probably regulates the methylation-sensitive gene expression. The drought-induced changes in DNA methylation would contribute for epigenetic mechanism. The study provided evidence to argue that drought-induced increased methylation might be one of the major mechanisms associated with acclimation responses in field crops like rice.

White Guinea yam (Dioscorea rotundata Poir.) is indigenous to West Africa, a region that harbours the crop's tremendous landrace diversity. The knowledge and understanding of local cultivars’ genetic diversity are essential for properly managing genetic resources, conservation, sustainable use and their improvement through breeding. This study aimed to dissect phenotypic and molecular diversity of white yam cultivars from Benin using agro-morphological and single nucleotide polymorphism (SNP) markers. Eighty-eight Beninese white Guinea yam cultivars collected through a countrywide ethnobotanical survey were phenotyped with 53 traits and genotyped with 9725 DArT-SNP. Multivariate analysis using phenotypic traits revealed 30 traits as most discriminative and explained up to 80.78% of cultivars’ phenotypic variation. Assessment of diversity indices such as Shannon–Wiener (H′), inverse Shannon (H.B.), Simpson's (λ) index and Pilou evenness (J) based molecular and phenotypic data depicted a moderate genetic diversity in Beninese white Guinea yam cultivars. Genetic differentiation of cultivars among country production zones was low due to the high exchange of planting materials among farmers of different regions. However, there was high genetic diversity within regions. Hierarchical clusters (HCs) on phenotypic data revealed the presence of two groups while HCs based on the SNP markers and the combined analysis identified three genetic groups. Our result provided valuable insights into the Beninese white Guinea yam diversity for its proper conservation and improvement through breeding.

Plant genetic resources (PGR) include cultivars, landraces, wild species closely related to cultivated varieties, breeder's elite lines and mutants. The loss of genetic diversity caused by the practice of agriculture and the availability of genetic information has resulted in a great effort dedicated to the collection of PGR. Prior to the advent of molecular profiling, accessions in germplasm collections were examined based on morphology. The development of molecular techniques now allows a more accurate analysis of large collections. Next-generation sequencing (NGS) with de novo assembly and resequencing has already provided a substantial amount of information, which warrants the coordination of existing databases and their integration into genebanks. Thus, the integration and coordination of genomic data into genebanks is very important and requires an international effort. From the determination of phenotypic traits to the application of NGS to whole genomes, every aspect of genomics will have a great impact not only on PGR conservation, but also on plant 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.

Genetic improvement along with widened crop base necessitates for the detailed understanding of the genetic diversity and population structure in wheat. The present investigation reports the discovery of a total of 182 alleles by assaying 52 simple sequence repeats (SSRs) on 40 genotypes of bread wheat. Unweighted neighbour-joining method grouped these genotypes into two main clusters. Highly heat tolerant and intermediate tolerant cultivars were grouped in the same cluster, whereas remaining genotypes, particularly sensitive ones, were assigned different cluster. Similarly, the entire population was structured into two sub-populations (K = 2), closely corresponding with the other distance-based clustering patterns. The marker-trait association was discovered for four important physiological parameters, viz. canopy temperature depression, membrane thermostability index (MSI), normalized difference vegetation index and heat susceptibility index, indicating for heat stress (HS) tolerance in wheat. Both general and mixed linear models of association studies during 2017 and 2018, revealed the association of SSR markers, wmc222 (17.60%, PV) and gwm34 (20.70%, PV) with the mean phenotypic value of MSI. Likewise, SSR markers barc183, gwm75, gwm11 and cfd7 revealed a unique relationship with four selected physiological traits. Candidate genes discovered using in silico tools had nine SSR markers within the genic regions reported to play a role in heat and drought stress responses in plants. The information generated about these genic regions may be explored further in expression studies in-vivo to impart HS tolerance in bread wheat.

The landraces of rice (Oryza sativa L.) possess wide diversity, which needs to be properly characterized for their use in genetic improvement. Replicated field studies were conducted in 1998, 1999 and 2000 at two sites in Nepal to determine diversity in 183 landraces of rice adapted to the lowlands and the hills in Nepal. Fourteen improved genotypes were also used for comparison. Thirteen agronomic traits were investigated. Shannon–Weaver diversity index (H) and Simpson's index of diversity (D) were estimated to determine the level of genetic richness among the landraces. The landraces differed significantly for all traits. Except for plant height and maturity, at least one of the landraces compared well with the performance of improved cultivars. A principal component analysis separated the lowland- and hill-adapted landraces into two broad groups.

Prunus avium cultivars widely used in northern Greece were investigated in terms of inter- and intra-cultivar genetic variation and DNA fingerprinting. Based on 11 simple sequence repeats loci, the average number of alleles per locus (Na = 2.82), probability of identity (PID = 0.327), polymorphic information content (0.451) and expected heterozygosity (He = 0.494) were within the range reported in similar studies. The most informative markers were BPPCT039 and EMPa018. The cultivars were clearly separated in both an unweighted pair group method with arithmetic mean dendrogram and a multivariate space ordination. Any two cultivars differed on the average at 6.30 loci. The null hypothesis of zero intra-cultivar variability was tested and could not be rejected. Two cultivars (Tragana Edessis and Tragana Sarakinon) were genetically similar, but not identical. This study, the first of its kind for sweet cherry in Greece, presents a useful molecular tool for resolving issues of intra-cultivar variability and synonimity and provides a warranty of genetic identity in the handling and management of local traditional germplasm.