In drought-affected maize production zones with short growing periods, the development and use of early maturing drought-tolerant cultivars can stabilize maize production. We evaluated 10 improved and 25 farmers' early maturing maize varieties under moisture deficit and well-watered conditions for 2 years to identify suitable genetic materials for breeding drought-tolerant cultivars. The varieties exhibited significant differences in grain yield and other traits under both moisture deficit and well-watered conditions. Changes in the rank order of the varieties for grain yield was not significant across the different levels of moisture supply in this study. Grain yield was significantly correlated with days to anthesis, days to silking, plant height, ear height, ear number and anthesis–silking interval (ASI) under the two irrigation treatments and with leaf death scores under moisture deficit, suggesting that the common traits were beneficial in maximizing grain yield under both sufficient water supply and moisture deficit. Grain yield and the traits significantly correlated with it differentiated the early maturing maize varieties into two distinct groups under well-watered condition and moisture deficit. The improved varieties were superior to the farmers' varieties in grain yield and other traits under moisture deficit, possibly due to selection of their progenitors for improved performance in multiple locations. We found some farmers' and improved varieties with similar yield potential and flowering time under well-watered conditions but with marked differences in grain yield and other traits under moisture deficit. Use of such promising landraces that would also be invaluable sources of desirable farmers-preferred end-use quality traits in combination with promising improved varieties as breeding materials could enhance the genetic grain from selection for drought tolerance in early maize.

In recent years, there has been an increased interest in Europe and in the USA in grafting watermelon onto bottle gourd, Lagenaria siceraria (Mol.) Standl. In this study, genetic diversity and relationships were examined [using 236 sequence-related amplified polymorphism markers] among 56 United States plant introductions (PIs) of L. siceraria and PIs of important cucurbit crops [including Cucurbita maxima Duchesne (winter squash), Cucurbita pepo L. (squash and pumpkin), Citrullus spp. (watermelon), Cucumis melo L. (melon) and Cucumis sativus L. (cucumber)]. The analysis showed that L. siceraria is distinct and has similar genetic distances to the cucurbit species examined herein. The L. siceraria PIs were assembled into two major clusters. One cluster includes groups of PIs collected mostly in South Asia (India) and a few PIs collected in the Mediterranean region and in Northeast Africa. The second cluster includes groups of PIs collected mainly in Southern Africa and in North, Central and South America, and PIs collected in China, Indonesia and Cyprus. All L. siceraria PIs in this study were susceptible to the southern root-knot nematode (RKN) [Meloidogyne incognita (Kofoid and White) Sandground]. However, several PIs, among them a group of closely related PIs collected in Mexico and Florida, were less infected with southern RKNs. All L. siceraria PIs were infested with whiteflies [Bemisia tabaci (Gennadius)], while several PIs were less infested than others and need further evaluation and selection for developing breeding lines that may be less appealing to this pest. Most of the PIs that showed resistance to zucchini yellow mosaic virus and tolerance to powdery mildew were collected in India and belong to the same phylogenetic groups (PGs). Experiments with L. siceraria PIs representing different PGs showed similar grafting compatibility with watermelon. Findings from this study should be useful for the development of superior L. siceraria rootstock lines with enhanced resistance to diseases and insect pests of cucurbit crops.

Plant viruses pose a threat to the acquisition, maintenance and distribution of lupin germplasm (genus Lupinus, family Fabaceae). The availability of sufficient quantities of healthy and virus-free seeds from maintained lupin collections is mandatory for conducting lupin research. The objective of this research was to determine which lupin species were potentially infected with potyviruses (presumably seed-borne) upon germination in the greenhouse. The procedure for screening lupin seedlings in the greenhouse for potyviruses incorporated enzyme-linked immunosorbent assay followed by elimination or segregation of infected seedlings from the population before transplantation into the field plots for regeneration and accession characterization. None of the accessions in this evaluation had been tested previously for virus. From 2002 to 2005, 15 perennial (30 accessions) and 6 annual lupin species (213 accessions) were evaluated on site at the Western Regional Plant Introduction Station in Pullman, WA, USA. While none of the greenhouse perennial seedlings tested positive for potyvirus, seedlings in three annual species (Lupinus albus, Lupinus angustifolius and Lupinus luteus) were infected by potyviruses, presumably by seed transmission. Future testing may focus on the annual species, thus saving limited germplasm maintenance resources.

A collection of 18 landraces of common bean (Phaseolus vulgaris L.) from northern Portugal was evaluated for both phaseolin pattern and a set of qualitative and quantitative traits. The phaseolin Contender and Tendergreen types were the most commonly occurring, with Boyaca and Huevo de Huanchaco present, but rare. The colour of the flower standard and wing, and seed shape, colour and size were all highly variable. On the basis of morphological traits, the landraces and testers clustered into two main groups. No relationship was found between phaseolin profile and any of the quantitative traits measured. Based on phaseolin patterns, the origin of Portuguese common bean populations was probably the Andean region of South America.

The Germplasm Enhancement of Maize (GEM) Project is a cooperative effort between the USDA-ARS, private industry and public researchers to broaden and enhance the germplasm base of maize. In this program, selected accessions from the Latin American Maize Project, and seven tropical hybrids donated by DeKalb to the GEM Project, were crossed to elite proprietary inbred lines contributed by commercial plant breeding programs. In most cases, the resulting hybrids were crossed to a second commercial inbred line and the resulting 25% exotic hybrids were used as breeding populations for further development. To identify GEM germplasm with value to protein quality breeding programs, we developed a process for evaluating the content of the essential amino acids methionine, lysine and tryptophan in the grain of GEM germplasm that balances the need for multiple-year evaluations with the constantly changing entry list of this germplasm screening program. This process involves annual field trials with common checks. Weak entries are dropped from the trial each year to make room for new entries, while strong entries are retained. Methionine exhibited the most significant variation, followed by lysine and then tryptophan. A number of GEM lines had methionine or lysine levels that were significantly better than Corn Belt checks and some were competitive with high-amino acid checks.

Genetic diversity and relationships among 112 mango (Mangifera indica) plants native to 16 states of Mexico and four controls [three mango cultivars (Ataulfo, Manila and Tommy Atkins) and one accession of Mangifera odorata] were evaluated based on amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) molecular markers. Mango germplasm shows broad dispersion through Mexico and genetically similar germplasm from different agroecological regions has previously been found by our group. Both AFLP and SSR analyses indicated high genetic similarity among mango populations that were clustered in two major groups: mangos from Gulf of Mexico coastline and mangos from Pacific Ocean coastline and locations far away from the sea. The highest genetic diversity was found within plants from each state, and significant genetic differentiation (FST = 0.1921, AFLPs and 0.1911, SSRs) was also observed among mango populations based on geographical origin and genetic status (cultivars versus landraces). Heterozygosity values ranged from low (0.38) to moderate (0.68), and no heterozygote deficits were found. The highest genetic variability was found in mango populations from Tabasco, Michoacán and Oaxaca. Data suggested that mangoes are subjected to natural or induced pollination, so segregation as well as genetic recombination plays major roles on genetic diversification of Mexican mangos. AFLP analysis was more robust than SSR for determining the genetic relationships among mango landraces from Mexico.

The fatty acid composition of peanut seed oil from a range of samples included in the core of the core or the ‘mini core’ of the US peanut germplasm collection was determined using gas chromatography. Oil contents of the seeds ranged from 31.4 to 47.9%. Very long-chain fatty acids are defined as those having more than 22 carbons in chain length. Although it has been reported in peanuts seed previously, the presence of hexacosanoic acid (C26:0) was quantified in a large variety of samples here for the first time along with docosanoic (C22:0) and tetracosanoic acids (C24:0) to demonstrate the potential of peanut seed as a source of very long-chain fatty acids that have been associated with widely varying effects such as the metabolism of the dietary fatty acids and physical properties of the oils themselves. Use of representative samples from the peanut germplasm collection allowed for comparison of very long-chain fatty acid content among seeds of different origins, and showed, although values overlapped, the seeds did cluster according to area of origin.

At 50% maturity, regenerating Senna species were characterized for morphological traits, seed reproduction, and evaluated for regeneration. Quality plants regenerated from all accessions produced 1018 to more than 21,215 total seeds. Principal component analysis revealed which traits contributed the greatest to variability among coffee senna accessions. Senna species have potential to produce pharmaceutical products and can be grown as medicinal plants. The flavonoids quercetin and kaempferol found in Senna species have been clinically shown to have anti-pancreatic cancer properties.

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.

Synthetic amphiploids between Triticum aestivum (AABBDD) landrace Chinese Spring (PhI) and cultivar WL711 with different accessions of Aegilops kotschyi (UUSlSl) were developed through colchicine treatment of sterile hybrids. The F1 hybrids and amphiploid plants were intermediate between the parents for plant morphology and spike characteristics. Meiotic metaphase chromosome analysis of the F1 hybrids (ABDUSl) showed the expected chromosome number (35) and very little but variable homoeologous chromosome pairing. The amphiploids (AABBDDUUSlSl), however, had variable frequency of univalents at meiotic metaphase-I. The SDS–PAGE of high molecular weight glutenin subunits of amphiploids along with the parents showed the presence and expression of all the parental genomes in the amphiploids. The amphiploids with seeds as large as that of wheat cultivars had higher grain, flag leaf and grain ash iron and zinc concentrations than the wheat parents and comparable with those of their Ae. kotschyi parents suggest that Ae. kotschyi possesses a distinctive genetic system for the micronutrient uptake, translocation and sequestration than the wheat cultivars. This could, however, be demonstrated unequivocally only with comprehensive data on biomass, grain yield and harvest index of the Aegilops donors and the synthetic amphiploids, which is not feasible due to their shattering and hard threshing. The use of amphiploids for the transfer of high iron and zinc concentrations and development of alien addition and substitution lines in wheat is in progress.

DNA fingerprinting using microsatellites is a useful aid in cultivar identification, but has rarely been applied to garden plants. Eleven microsatellite markers were developed for the valuable garden plant Hesperantha coccinea (Schizostylis coccinea), and used to determine relatedness of accessions. Several accessions, described as separate cultivars, appeared to have identical genotypes. Among the 53 accessions tested, there were 34 unique multilocus genotypes. The level of polymorphism detected in the cultivars was high, with on average seven alleles per locus and an average expected heterozygosity of 0.72 across loci. It is clear from the genotypes that a large proportion of the cultivars are closely related to each other. The resulting markers can now be used to generate a complete database of all known cultivars of the species and to detect essentially derived cultivars. As an extension of this study, the markers identified here could also inform us about the genetic diversity in wild populations.

We present here the first comprehensive genetic characterization of snapmelon landraces from the humid tropics of eastern India. The genetic diversity among 42 snapmelon landraces collected from four agro-ecological regions of eastern India (eight agro-ecological subregions) was assessed by measuring variation at 16 simple sequence repeat (SSR) marker loci, at various traits including plant habit and fruit type, yield (two associated traits), disease resistance and biochemical composition (total soluble solids, ascorbic acid, carotenoids and titrable acidity). Differences between accessions were observed in a number of plant and fruit traits. Snapmelon germplasm with high acidity, elevated carotenoid content and resistance to cucumber mosaic virus were identified in the collection. The SSR analysis indicated that there is a high level of genetic variability within snapmelon germplasm. Comparison of the genetic variability between snapmelons of eastern India and melons from north, south and central regions of India and reference accessions of melon from Spain, France, Japan, Korea, Maldives, Iraq, Zambia, Israel using SSRs showed that Indian snapmelon germplasm is not closely related to melon accessions from other parts of the world and that there are regional differences between Indian melon accessions. Eastern India snapmelon has unique traits, so it is important that more germplasm from this region is sampled and preserved.