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.

Gloriosa superba L. is a highly valued indigenous medicinal plant. It is available throughout India with noticeable variations in morphology and colchicine content. In the present study, morphological, phytochemical, cytological and molecular data are employed to screen the polymorphism, if present, in five different populations of G. superba L. Based on gross morphological traits, the plants can be grouped into two clusters: Amtala (AM) and Baruipur (BR) plants belonging to one cluster, and Siliguri (SG), Darjeeling (DJ) and Sikkim (SK) plants belonging to the other. Colchicine content of the tubers ranged from 0.06% in AM plants to 0.37% in BR plants. Cytological analysis revealed that the SK plants showed 44 chromosomes, i.e. tetraploid status, whereas the other four were diploid. Assessment of the karyomorphology of the four diploid populations indicated a close similarity between AM and BR plants, whereas the SG plants exhibited slightly different karyomorphology and lacked sm-type chromosomes. Random Amplified Polymorphic DNA (RAPD) analysis revealed 76% polymorphism among the populations. Cluster analysis using RAPD resulted in three main cluster groups; BR and SG plants clustered together indicating that they are most closely related when compared with other populations.

To date, there are only a few sequenced-tagged site (STS) markers associated with genes controlling fruit quality in watermelon. A normalized cDNA library for watermelon fruit (Citrullus lanatus var. lanatus) was constructed. Sequence analysis of the cDNA clones resulted in the development of 4700 non-redundant ESTs (EST unigenes) expressed in watermelon fruit (http://www.ncbi.nlm.nih.gov, http://www.icugi.org). One hundred of these EST unigenes [including 40 EST unigenes that contain simple sequence repeat (SSR) motives (EST-SSRs) and 60 customary EST unigenes (not containing SSR motives)] were used for designing primer pairs for PCR experiments. The EST primer pairs were tested in PCR experiments with genomic DNA of 25 watermelon heirloom cultivars and 13 United States Plant Introductions (US PIs) of Citrullus sp., including four C. lanatus var. lanatus, five C. lanatus var. citroides PIs and four Citrullus colocynthis PIs. The 40 EST-SSR and 60 EST primer pairs produced 108 and 142 EST-PCR markers, respectively, among the Citrullus PIs and watermelon cultivars. A large number of the EST-PCR markers were polymorphic between the Citrullus PIs and the watermelon cultivars, but significantly less polymorphic among the cultivars. Of the 108 EST-PCR markers associated with EST-SSRs, 103 exist in the Citrullus PIs and 64 in the cultivars. Of these 64 markers, 45 (70.3%) were polymorphic among the cultivars. Of the 142 EST-PCR markers associated with customary ESTs, 134 exist in the Citrullus PIs and 108 in the cultivars. Of these 108 markers, 86 (79.6%) were polymorphic among cultivars. The results in this study indicate that polymorphism exists in coding regions of genes expressed in fruits of watermelon cultivars. In total, 131 polymorphic EST-PCR markers (45 associated with EST-SSRs and 86 associated with customary ESTs) related to watermelon fruit genes were generated using the above data. These markers should be useful for DNA fingerprinting of cultivars and breeding lines, for assessing genetic relationships and for genetic mapping of watermelon.

The genus Limnanthes (Limnanthaceae), also known as meadowfoam, has attracted attention for industrial use due to the unique characteristics of its seed oil. Samples from wild populations showed variability in agronomically important traits involved in seed oil yield, warranting the establishment and continued development of a germplasm collection. The level of genetic diversity within the United States Department of Agriculture, Agriculture Research Service, National Plant Germplasm System (USDA-ARS-NPGS) Limnanthes collection was evaluated using 15 simple sequence repeat (SSR) markers across 62 accessions representing 7 species. Parsimony analysis separated the accessions into two main groups consistent with the traditional taxonomic sections Inflexae and Reflexae, but there was little resolution within groups. These two groups were confirmed using neighbour-joining analysis and principal coordinate analysis. SSR marker variation suggests that the Limnanthes germplasm collection is genetically diverse and the accessions within the species likely contain novel alleles, and therefore the collection contributes to the conservation of the wild Limnanthes gene pool.

Helianthus annuus and H. petiolaris (Asteraceae) are wild sunflowers native to North America but have become naturalized in central Argentina covering an area of about 5 million hectares. Wild H. annuus has been recognized as invader species in several countries, but no research has been done to study the ecological determinants of their distribution. In a survey covering seven provinces between 31°58′–38°S and 60°33′–69°W, we described the ecology of the main wild populations. Wild Helianthus populations were located in three of the 18 ecological regions of Argentina, on five Mollisol and seven Entisol soil groups. The associated plant communities were comprised 60 species belonging to 16 families, all being frequent components of the native flora. Disease symptoms were seldom observed in wild populations, with Alternariahelianthi being the most commonly observed pathogen. Population size varied from less than 100 to more than 100,000 plants, covering from 100 to more than 60,000 m2 with densities most frequently up to 3 plants/m2, but reaching 80 plants/m2 at certain sites. Intermediate plant phenotypes between wild species and cultivated sunflower were found in one-third of the populations providing evidence of intense gene flow. Hybrid swarms were found at three localities with population sizes between 100 and 10,000 individuals.

Season-long monitoring of on-farm rice (Oryza sativa, L.) plots in Nepal explored farmers' decision-making process on the deployment of varieties to agroecosystems, application of production inputs to varieties, agronomic practices and relationship between economic return and area planted per variety. Farmers deploy varieties [landraces (LRs) and modern varieties (MVs)] to agroecosystems based on their understanding of characteristics of varieties and agroecosystems, and the interaction between them. In marginal growing conditions, LRs can compete with MVs. Within an agroecosystem, economic return and area planted to varieties have positive relationship, but this is not so between agroecosystems. LRs are very diverse on agronomic and economic traits; therefore, they cannot be rejected a priori as inferior materials without proper evaluation. LRs have to be evaluated for useful traits and utilized in breeding programmes to generate farmer-preferred materials for marginal environments and for their conservation on-farm.

Rice varietal diversity was assessed in Guinea on the basis of surveys of 1679 farms located in 79 villages of the four natural regions of the country. The descriptors used were the number of known varieties, the number of cultivated varieties and Shannon's diversity and evenness index. On the basis of their use rates, varieties were classified as major or minor types at the village scale and as regionally and/or nationally eminent varieties at these scales. Varietal diversity was high, especially in forest Guinea and lower Guinea. Diversity pattern was typical of the subsistence farming system. The high share of local variety reflected the predominance of low management and low input cropping systems. The presence of improved varieties confirms farmers' openness to innovation and to the government policy of promoting improved varieties. Regional diversity reflected the agro-ecological diversity and specificities of each region, the history and the extent of rice-growing systems, and the importance of rice in the local diet. Recent dissemination of NERICA varieties has not caused any reduction of pre-existing varieties. The short-duration NERICA are mainly used as a complement to the long-duration traditional varieties and thus enhance varietal diversity. Risks of diversity erosion seem limited in the current setting of farming system and diversity structure. However, at the village level, the diversity pattern is fragile as the proportion of farmers who used each variety of the village is low and heterogeneous. A continuous monitoring of the dynamics of rice varietal diversity in Guinea is needed.

False brome grass, Brachypodium distachyon (L.) Beauv, has been proposedas a new model species to bridge rice and temperate cereal crops for genomics research.However, much basic information for this species is still lacking. In this study, sixdiploid B. distachyon(2n = 2x = 10)accessions (Bd1-1, Bd2-3, Bd3-1, Bd18-1, Bd21 and BD29) were evaluated for their responseto infestation by two cereal aphid pests of common wheat (Triticumaestivum L.): the greenbug, Schizaphis graminum Rondani, and theRussian wheat aphid (RWA), Diuraphis noxia Mordvilko. Through databasemining of B. distachyon expressed sequence tag (EST) and genomic DNAsequences, 160 EST- and 21 genomic microsatellite markers were developed and used toevaluate genetic diversity among the B. distachyon accessions. All sixaccessions were resistant to RWA biotype RWA1 but showed distinct responses to feeding bygreenbug biotypes C and E, as well as RWA2 RWAs. Although microsatellite-based geneticdiversity among different accessions was generally low, Bd1-1 and BD29 were the mostdiverged from the other four lines. The genetic divergence was correlated withgeographical distances between the Brachypodium accessions. Comparison ofsimple sequence repeat polymorphisms in three inbred lines (Bd2-3, Bd3-1 and Bd18-1) withtheir respective original parental lines revealed no effect of inbreeding on geneticdiversity. Phylogenetic analysis suggested that Aegilops tauschii (Coss.)Schmal., the D genome donor of common wheat, was closer to B. distachyonthan to rice. The greenbug - B. distachyon system seemsto be a model of choice for plant–aphid interaction studies in the grassgenome.

trans-Resveratrol (trans-3,4′,5-trihydroxystilbene), a polyphenolic compound uniquely identified in plants, is believed to greatly contribute to human health. Peanut (Arachis hypogaea L.) seeds of 20 germplasm accessions were harvested from the same field and used for resveratrol analysis by high-performance liquid chromatography. trans-Resveratrol content in air-dried peanut seeds was on average about 0.5 μg/g and a statistically significant variation (from 0.125 to 1.626 μg/g, at least a ten-fold difference) was detected among the accessions analysed. The average weight for 100 seeds was 52.84 g. A statistically significant variation in seed weight (from 22.30 to 87.94 g, at least a four-fold difference) was observed. There was no significant correlation between trans-resveratrol content and seed weight. The information about the levels of trans-resveratrol in peanut seeds will be useful for peanut cultivar development and peanut product processing. Breeders could use germplasm accessions containing a high amount of resveratrol to develop new nutritionally improved peanut cultivars and food processors could use these new cultivars to manufacture high resveratrol peanut products.

Nine characters contributing to seed yield were measured on 20 accessions of horse gram (Macrotyloma uniflorum (Lam.) Verd), and subjected to genetic divergence analysis using Mahalanobis statistic and mapping using DIVA-GIS. The accessions were collected from two eco-geographical regions of Andhra Pradesh (India) – North Coastal and Rayalaseema. Based on D2 values the genotypes were grouped into five clusters. Genetic diversity was not related to eco-geographical distribution. The greatest inter-cluster distance separated clusters II and V, followed by clusters IV, and V, III and IV. Entries in clusters V and II appear suitable as parents for horse gram improvement. The Rayalaseema region is the source of useful variation for days to flowering, maturity and yield.

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.