Mungbean seeds are often attacked by bruchid insects causing serious damage to the grain during storage. The susceptible/resistant characteristics of mungbean against bruchids have been investigated at the protein level. Seeds of the susceptible cultivar Osaka-ryokuto and the resistant near-isogenic line BC20 were collected at 5, 9, 13, 17, 21 and 23 days after flowering. Crude, cytosol and membrane protein fractions were extracted from the seeds for twodimensional polyacrylamide gel electrophoresis analysis. In Osaka-ryokuto six proteins were found in higher amounts compared to BC20 in the crude protein extract. Some of these proteins were homologous to legumin B and liguleless1. And in BC20 one unique protein, homologous to SalF1R, was identified. In the subcellular protein fractions, nine unique proteins were identified in BC20, seven in the cytosol and two in the membrane fractions. These proteins were homologous to chitinase, alanine aminotransferase in membrane, and SalF1R, β-1,3- glucanase, protein phosphatase 2A, peroxidase BP 2A, provicilin and canavalin in the cytosol fractions. Previous findings of many researchers reveal that these are mainly defence-related proteins. Thus, it is suggested that the above proteins may play a role in maintaining the resistance of line BC20.

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most important diseases affecting wheat. In this study, seven gene-linked markers were used to identify the presence of stripe rust resistant genes in 51 accessions of synthetic hexaploid of wheat which were found to be resistant at seedling plant stage. Molecular marker-based gene identification showed the presence of Yr5, Yr10 and Yr15 in three accessions, Yr36 in three accessions, Yr48 in seven accessions, YrR61 in four accessions, and YrTP1 in ten accessions of resistant hexaploid of wheat. These gene-linked markers were also used for the detection of genetic diversity. A total of 68 alleles were detected by these seven gene-linked markers. The mean number of allele was 11.3 alleles per locus. Genetic diversity values ranged from 0.34 to 0.93, with highest genetic diversity value of 0.93 detected for marker Xwm477. The lowest genetic diversity value was observed for marker Xbarc167. The polymorphic information content value ranged from 0.33 to 0.92 with an average of 0.54. The highest number of alleles (n= 24) were detected for marker Xwmc477. The evidence in this study on the basis of genetic diversity and presence of Yr genes in synthetic hexaploid wheat accessions will be useful in further breeding programmes.

Inter simple sequence repeat markers were used to assess the genetic diversity and population genetic structure in 12 populations of Nothapodytes nimmoniana from Western Ghats of India. A total of 16 selected primers produced 103 discernible bands, with 76 (73.7%) being polymorphic. The Nei's gene diversity (h) ranged from 0.1166 to 0.2124, with an average of 0.1518 at the population level and 0.2965 at the species level indicating high genetic diversity. The Shannon's index (I) was estimated to be 0.2189 within populations (range 0.1703–0.2947) and 0.4352 at the species level. The analysis of molecular variance showed that the genetic variation was found mainly within populations (73%), but variance among populations was only 27% and its value, ΦPT = 0.271, P < 0.001, implied that high genetic differentiation among populations. In addition, Nei's differentiation coefficient (GST) was found to be high (0.4882) and the gene flow (Nm) was low (0.5242), confirming the high population genetic differentiation. The unweighted pair-group method using arithmetic average clustering elicited similar results. Based on this, we propose conservation strategy for this plant species.

Three hundred and seventeen grape accessions from the National Active Grape Germplasm Site in India were analysed with 25 microsatellite markers. A total of 411 alleles were detected, of which 42% were rare alleles. Unique alleles for 56 genotypes were also identified. The analysis of microsatellite data identified 63 duplicate accessions and only 254 accessions were unique genotypes. Several cases of misnomers, synonymy and homonymy were identified. Parental genotype for a few clonal selections was ascertained. Population structure analysis grouped 254 unique genotypes into four major clusters. The analysis also revealed the presence of admixtures with only 79% of pure ancestry. A core collection comprising 80 genotypes was identified, which represented all the alleles and genetic diversity. A user-friendly and interactive computer application software was developed for storage and the retrieval of molecular data. A molecular database for the 254 genotypes was created. This analysis will help in the rationalization and better management of germplasm. Information on genetic diversity and population structure will form the basis for varietal improvement programmes.

Higher seedling vigour and greater coleoptile length are important for early establishment of wheat crops and subsequently higher grain yield in many dry environments. Seedling vigour includes those seed properties that determine the potential for rapid, uniform emergence and development of normal seedlings under a wide range of field conditions. Genotypes with the widely used gibberellic acid (GA)-insensitive dwarfing genes Rht-B1b and Rht-D1b have good partitioning and grain yield under optimal conditions, but may perform poorly under stressed conditions due to poor crop establishment. Breeding programmes are in search of GA-sensitive dwarfing genes that do not affect seedling vigour under dry conditions. This study evaluated 40 genotypes currently used in wheat breeding programmes of south Asia for seedling vigour-related traits in greenhouse and field experiments during 2006–2007 at IAAS, Rampur, Nepal. Wide variation in coleoptile length, seedling vigour, as well as sensitivity to GA was observed. Among the genotypes studied, there were positive correlations among coleoptile length, leaf width and plant height. Genotypes, SW89-5193, SW89-5422/NL251 and SW89-5422, were found to have longer coleoptile, higher seedling vigour and response to GA application. This shows a promise for their further applications in the breeding programmes.

Response to selection is fundamental to plant breeding. To gain insight into the genetic basis of response to selection, we propose a new experimental genetic framework allowing for the identification of trait-specific genomic loci underlying population improvement and the characterization of allelic frequency responses at those loci. This is achieved by employing a sampling scheme for recurrently selected populations that allows for the simultaneous application of genetic association mapping and analysis of allelic frequency change across generations of selection. The combined method unites advantages of the two approaches, permitting the estimation of trait-specific allelic effects by association mapping and the detection of rare favourable alleles by their significant enrichment over generations of selection. Our aim is to develop a framework applicable for many crop species in order to gain a broader and deeper understanding of the genetic architecture of response to artificial selection.

It is known that genetic diversity is the most important factor in classical and modern plant breeding. The considerable increase in the number of transgenic crops reveals the value of new plant genetic resources. In this study, a set of 12 wheat progenitors were screened for tissue culture parameters such as callus induction, callus weight, regeneration capacity of callus and callus efficiency using mature embryos. Embryos were excised from imbibed seeds of the progenitors. The excised embryos were placed scutellum upwards in dishes containing 2 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D) for callus induction. The developed calli and regenerated plants were maintained on 2,4-D free MS medium. When mature embryos of 12 wheat progenitors (Aegilops sp. and Triticum sp.) were compared, significant differences were detected in callus induction frequency, weight of callus, regeneration capacity and culture efficiency. A significant genotypic effect was observed on the culture responses. Of the 12 wheat progenitors tested, Aegilops umbellulata had the highest regeneration capacity of callus. Aegilops biuncialis created the most regenerable calli because of the highest callus induction and culture efficiency. In the experiment, callus induction was significantly correlated with callus weight (r= 0.820) and regeneration capacity (r= 0.955). Weight of callus was significantly correlated with regeneration capacity (r= 0.740), while there was no significant correlation between callus induction frequency and culture efficiency (r= 0.350). Our results showed that, generally, mature embryos of some Aegilops and Triticum species have a high regeneration capacity, and therefore, can be used as an effective explant source for the successful application of biotechnology in crop improvement.

This study assessed the genetic diversity of African yam bean (AYB) accessions using morphological and molecular markers. The accessions were grown, and morphological data collected were subjected to analysis of variance and multivariate analyses. Genomic DNA extracted from the accessions were amplified with inter simple sequence repeat (ISSR) markers. The diversity analysis was conducted using MEGA4 software. The accessions varied significantly (P < 0.05) in growth, flowering and seed-related parameters. Flowering commenced early in most accessions. Weight of 100-seed range from 15.01 to 21.15 g with the mean value of 18.30 g. Significant correlations existed between stem height, the number of leaves and leaf dimensions. Also, days to flowering correlated with pod formation; likewise, seed dimension had a positive association with seed weight. The principal biplot revealed that two components accounted for 41.77% of the observed variation. Analysis of the electropherogram showed 95 loci comprising 1351 alleles were detected by the ISSR markers with 65.26% polymorphism and combined polymorphic information content of 0.85. The principal coordinate analysis placed accessions together on a plane based on their spatial relationship. The dendrogram showed accession pairs (TSs-77, TSs-95) and (TSs-111, TSs-84) are closely related. The phylogram identified three kinships with a total length of 454. Accession TSs-115 is likely the progenitor while TSs-82 and TSs-86 are the most recent. The study concluded that a combination of morphological and ISSR markers is effective for the diversity study of AYB and the existing, genetic diversity in the accessions could be harnessed for its improvement, conservation and utilization.

North Africa enclosed original apricot genetic resources with the cohabitation of grafting and seed-propagated accessions. In this study, we assessed the genetic diversity and population structure of 183 apricot accessions using 24 microsatellite markers distributed evenly in the Prunus genome. A total of 192 alleles and a high level of gene diversity (0.593) were detected among the whole panel. Genetic structure analysis revealed the presence of four genetic clusters. We also found that both geographical origin and mode of propagation are important factors structuring genetic diversity in apricot species. Results confirmed the presence of gene exchange between the northern and southern countries of the Mediterranean Basin. Subsequently, a core collection of 98 accessions based on M (maximization) strategy showing 99.47% of allele retention ratio was constructed. No significant differences for Shannon's information index and Nei's diversity index were observed between the core and entire collections. Our results provide an effective aid for future germplasm preservation and conservation strategies as well as genetic association studies development in relation to phenotypic data.

Vavilov (1935) described China as the earliest and largest independent centre of origin of cultivated plants. Gansu Province occupies the geographic centre of China. With an area of 454,000 km2, latitudes ranging from 32°3′N to 42°57′N and elevations varying from 500 to 6200 m, the province has an extremely diverse climate and topography. Stretching 1653 km along the ancient Silk Road, Gansu also has a long history of agriculture (6000 years) and for centuries was exposed to dynamic cultural exchanges between the East and the West. The unique combination of these conditions allowed rapeseed to be introduced from Europe and the Middle East, to evolve over a long time of cultivation and to diversify to adapt to many types of ecological conditions and cropping systems in Gansu. Currently, rich genetic resources exist in Gansu for Brassica rapa, B. juncea, B. chinensis and Eruca sativa. Eight landraces are described to demonstrate the diversity of rapeseed genetic resources in Gansu. It is generally recognized that B. chinensis originated in China. Information provided in this paper suggests that Gansu and its adjacent regions could also be a centre of diversity for B. rapa and B. juncea.

Despite Capsicum's importance in the Caribbean, comprehensive diversity studies of this species in the region are limited, especially regarding its morphological variation. This study evaluated 37 traits (seedling, vegetative and reproductive) in 201 accessions among four Capsicum species. Multivariate analyses revealed that (i) 54% of the quantitative (seedling and fruit) variation and (ii) 64% of the qualitative (floral and fruit) variation were explained by the first two components. The three main clusters identified did not immediately highlight geographic and species-specific separation. However, significance testing revealed some separation based on geographic subgroups and species assignment. Most Southern Caribbean accessions were considerably similar to each other (if not identical in some cases), thus providing opportunity to identify and remove duplicates from the collection. These Southern Caribbean accessions shared their greatest similarity with Upper Amazon accessions, and least similarity with Lower Amazon accessions, suggesting movement of material primarily from the Upper Amazon into the Southern Caribbean Basin. The dominant differentiating traits displayed in these Southern Caribbean accessions are probably due to strong active selection for certain morphotypes and not to founder effects. Upper and Lower Amazon accessions were largely well differentiated from each other, highlighting key underlying genetic differences between these two populations and possible ongoing barriers to germplasm exchange. Central American, Greater Antilles/Bahamas and Guiana Shield accessions shared similarities with both the Upper and Lower Amazon populations, hinting at probable introductions from both Amazon regions. Collectively, this provides essential baseline information on the morphological (and underlying genetic) relationships among these accessions to guide future characterisation and evaluation efforts on this collection.

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.

Triticum urartu Thum. ex Gandil. is a wild species identified as A-genome donor for polyploid wheats, which could be used as gene source for wheat breeding. The high-molecular weight glutenin subunits are endosperm storage proteins that are associated with bread-making quality. In T. urartu, these proteins are encoded by the Ax and Ay genes at the Glu-Au1 locus. The Ay gene of 17 Glu-Au1 allelic variants previously detected in this species has been analysed using PCR amplification and digestion of the PCR products with two endonucleases (DdeI and PstI). The combination of two restriction patterns has revealed variations between the active and inactive alleles, and within each type. This variation, especially that detected among the active alleles, could enlarge the high-quality genetic pool of modern wheat and be used for bread-making quality improvement in durum and common wheat.

The rice-based agriculture of the Indian subcontinent has been interwoven in the rich socio-cultural fabric of the country. Of which, bio-culturally diverse North-Eastern states nurture thousands of landraces with poorly tapped agronomic traits. In the present study, 27 standard microsatellite data from 171 rice landraces from six states were analysed to understand their genetic diversity and population structure. Further, combining with a global dataset, we determined subpopulation identity using both model-based and multivariate analyses to uncover their history. We found moderate to high genetic diversity and high differentiation [standardized G”ST = 0.57]. The AMOVA partitioned overall variance into within population (75%) and among population (25%). The landraces from six states remained at various degrees of differentiation (pairwise FST = 0.09–0.41). We have detected a preponderance of aus-type in a majority of aromatic landraces. Rests were japonica and admixed with a little representation of indica. The presence of aromatic aus probably implied assimilation into local culture from the primary aus growing region of Bangladesh and India. Likewise, the arrival of japonica may stem from the exchange of goods among neighbouring dynasties via Southern and Southwestern Silk routes. The shared ancestry may reflect a merger of two ancient cultures. Our analyses also uncovered the existence of aus-type short and medium grain aromatic rice predicting an origin of aroma in aus subpopulation. Collectively, it demonstrated the diversity and divergent history of the rice landraces have been shaped by various socio-cultural interactions operative over time and space.

The literature in recent times lacks adequate report on the utilization and genetic improvement programmes on Dioscorea dumetorum. Despite the wide application of this yam species in agriculture and medicine, it suffers neglect while other species are becoming increasingly popular. Therefore, it is pertinent to focus on research that will bring this species to the limelight. The aim of the present study was to evaluate the ploidy levels, morphological traits and secondary metabolite profile of 53 accessions of D. dumetorum from six countries in West and Central Africa. Ploidy levels were determined using flow cytometry. Overall, 18 morphological traits were recorded from the above- and underground parts of the plant. The 53 accessions were subjected to statistical analyses using the data on ploidy levels, morphological traits and qualitative phytochemical screening. A total of 15 accessions from the generated clusters were selected for thin layer chromatographic and quantitative phytochemical analyses. The analyses revealed diploid (2x) and triploid (3x) levels in these accessions. The pruned dendrogram derived from agglomerative hierarchical clustering based on the distance matrix revealed three main groups, showing a relationship between sex and ploidy level in the accessions and exhibiting sufficient cluster variability that may be important in designing breeding programmes. The crop was also shown to possess metabolites such as alkaloids, saponins and flavonoids, which are known to be useful in the application of phytomedicine. Genetic variability observed among the yam accessions in this study can be used for breeding purposes and to broaden the genetic basis of the crop for efficient utilization of the genetic potential possessed by this species.

The starchy corms of taro (Colocasia esculenta) are consumed throughout the tropics and are essential for food security in many developing countries. Taro corms are increasingly processed into fries, chips, flours or flakes in urban areas, and varieties with attractive corm flesh colours are now needed. The identification of flavonoids in taro corms would add value to this crop. The present study developed a high-performance thin layer chromatography (HPTLC) protocol for the high-throughput screening of flavonoids in taro germplasm. Overall, 350 different accessions were analysed including 259 varieties from Vanuatu, one from Vietnam, eight from Thailand, eight from the Philippines, six from Malaysia, two from Japan and 18 from Indonesia. Forty-eight breeding lines (hybrids) including 21 from Vanuatu, 21 from Samoa, four from Hawaii and two from Papua New Guinea were also analysed. Ten flavones, namely luteolin-6-C-hexoside-8-C-pentoside, schaftoside, luteolin-3′,7-di-O-glucoside, homoorientin, isovitexin, orientin, luteolin-4′-O-glucoside, luteolin-7-O-glucoside, vitexin and apigenin-7-O-glucoside, were successfully detected in the corm and are responsible for the attractive yellow colour of the flesh and fibres. Quantitatively, luteolin-6-C-hexoside-8-C-pentoside and schaftoside were the most important of all the detected flavonoids. However, only 18% of the varieties analysed presented these two compounds and 80% presented poor flavonoid composition. No geographical structure of the variation was detected and the most flavone-rich varieties originated from Vanuatu, Thailand, the Philippines, Malaysia and Indonesia. The compounds detected in the present study were significantly and positively correlated, suggesting that there is potential for fast improvement through controlled crosses, subsequent evaluation of full-sib progenies and cloning of elite individuals.

Knowledge of linkage disequilibrium (LD) patterns is considered a prerequisite for effective association mapping studies. However, no LD analysis in the Argentine public temperate maize collection has been reported to date. In this study, a panel of 111 temperate maize inbreds genotyped at 74 single sequence repeats (SSRs) loci was used to assess LD, genetic diversity and population structure to evaluate the suitability of the panel for association mapping. Mini-core sets were also designed for in-depth phenotyping and allele mining purposes. The panel consisted of: (1) locally developed orange flint germplasm; (2) temperate inbred lines with Iowa Stiff Stalk Synthetic background; and (3) eight historic flint lines, some of them from the Cuarentín race. As a result, four subpopulations were defined. Joint analysis of population structure and combining ability allowed identifying two main heterotic patterns. High molecular diversity, a low extent of LD and a high ratio of linked to unlinked SSR loci pairs in significant LD were detected indicating the suitability of the entire collection for association mapping. The fact that the LD extent in the mini-core sets was similar to that observed in the entire collection and that only a small percentage of allelic richness was reduced suggests that these mini-core sets are suitable to capture diversity, exploit phenotypic variance and discover useful variants representative of the entire collection.

The yield of durum wheat extremely reduces in response to salinity stress because of several variations in biochemical, physiological and molecular traits in this unfavorable condition. According to the agro-physiological traits under salinity stress, the most resistant and sensitive cultivars were selected from 10 genotypes of durum wheat over a period of 2 years. Afterwards, the molecular, biochemical, and physiological traits in these two genotypes were evaluated. The seedlings (3–4 leaves) were exposed to salinity through irrigating with 0.5 × Hoagland solution containing 200 mM NaCl until physiological maturity. Principal components analysis for the agronomic characteristics and stress resistance index led to identifying Behrang and Arya as the most tolerant and sensitive genotypes, respectively. In these two genotypes in response to salinity stress, osmolyte contents (proline, total soluble carbohydrates and total soluble proteins) and enzymatic antioxidant defence system activities (ascorbate peroxidase, catalase and guaiacol peroxidase) were much higher in the most tolerant genotype than those of the sensitive cultivar. Moreover, the most tolerant genotype showed less amount of oxidative stress parameters (hydrogen peroxide, electrolyte leakage, malondialdehyde and other aldehydes) than the sensitive one. Pyrroline-5-carboxylate reductase (P5CR) and delta-1-pyrroline-5-carboxylate synthase (P5CS) genes expression increased under salinity stress (considering much higher increase in the most tolerant cultivar). Also, proline content was shown to have a significant positive correlation with P5CS and P5CR genes expression levels. Our result not only identified Behrang cultivar as a superior genotype for durum wheat breeding programs, but also represented several efficient mechanisms involved in salt tolerance.

We now understand that many different types of DNA structural polymorphisms contribute to functional diversity of plant genomes, including single nucleotide polymorphisms, insertions of retrotransposons and DNA transposons, including Helitrons carrying pseudogenes, and other types of insertion–deletion polymorphisms, many of which may contribute to the phenotype by affecting gene expression through a variety of mechanisms including those involving non-coding RNAs. These polymorphisms can now be probed with tools such as array comparative genomic hybridization and, most comprehensively, genomic sequencing. Rapid developments in next generation sequencing will soon make genomic sequencing of germplasm collections a reality. This will help eliminate an important difficulty in the estimation of genetic relationships between accessions caused by ascertainment bias. Also, it has now become obvious that epigenetic differences, such as cytosine methylation, also contribute to the heritable phenotype, although detailed understanding of their transgenerational stability in crop species is lacking. The degree of linkage disequilibrium of epialleles with DNA sequence polymorphisms has important implications to the analysis of genetic diversity. Epigenetic marks in complete linkage disequilibrium (LD) with DNA polymorphisms do not add additional diversity information. However, epialleles in partial or low LD with DNA sequence alleles constitute another layer of genetic information that should not be neglected in germplasm analysis, especially if they exhibit transgenerational stability.