Mungbean (Vigna radiata) is a fast-growing, warm-season legume crop that is primarily cultivated in developing countries of Asia. Here we construct a draft genome sequence of mungbean to facilitate genome research into the subgenus Ceratotropis, which includes several important dietary legumes in Asia, and to enable a better understanding of the evolution of leguminous species. Based on the de novo assembly of additional wild mungbean species, the divergence of what was eventually domesticated and the sampled wild mungbean species appears to have predated domestication. Moreover, the de novo assembly of a tetraploid Vigna species (V. reflexo-pilosa var. glabra) provides genomic evidence of a recent allopolyploid event. The species tree is constructed using de novo RNA-seq assemblies of 22 accessions of 18 Vigna species and protein sets of Glycine max. The present assembly of V. radiata var. radiata will facilitate genome research and accelerate molecular breeding of the subgenus Ceratotropis.

Jatropha curcas (jatropha) is a potential biodiesel crop. A major limitation in production is that jatropha remains wild with low genetic variation. Related species/genera in the Euphorbiaceae can potentially be used for its genetic improvement. In this study, we employed inter-simple sequence repeats (ISSRs) to assess genetic variation among 30 accessions of jatropha, two accessions of bellyache bush (Jatropha gossypifolia), two accessions of spicy jatropha (Jatropha integerrima), two accessions of bottleplant shrub (Jatropha podagrica), and three accessions of castor bean hybrids. Genetic relationships were evaluated using 27 of 86 ISSR markers, yielding 307 polymorphic bands with polymorphism contents ranging from 0.76 to 0.95 for IMPN 1 and UBC 807 markers, respectively. Dice's genetic similarity coefficient ranged from 0.39 to 0.99, which clearly separated the plant samples into seven groups at the coefficient of 0.48. The first group comprised J. curcas from Mexico, the second group comprised J. curcas from China and Vietnam, the third group comprised J. curcas from Thailand, the fourth group was J. integerrima, the fifth group was J. gossypifolia, the sixth group was J. podagrica, and the last and most distinct group was Ricinus communis. Analysis of molecular variance revealed that 63% of the variability was attributable to variation among groups, while 37% was due to variation within groups. Based on Nei's genetic distance, the population from G2 (J. curcas from China) and G4 (J. curcas from Vietnam) had the least ISSR variability (0.0668), whereas G8 (R. communis) and Jatropha spp. displayed the highest distance (0.6005-0.7211).

Jatropha curcas (physic nut), a non-edible oilseed crop, represents one of the most promising alternative energy sources due to its high seed oil content, rapid growth and adaptability to various environments. We report ~339 Mbp draft whole genome sequence of J. curcas var. Chai Nat using both the PacBio and Illumina sequencing platforms. We identified and categorized differentially expressed genes related to biosynthesis of lipid and toxic compound among four stages of seed development. Triacylglycerol (TAG), the major component of seed storage oil, is mainly synthesized by phospholipid:diacylglycerol acyltransferase in Jatropha, and continuous high expression of homologs of oleosin over seed development contributes to accumulation of high level of oil in kernels by preventing the breakdown of TAG. A physical cluster of genes for diterpenoid biosynthetic enzymes, including casbene synthases highly responsible for a toxic compound, phorbol ester, in seed cake, was syntenically highly conserved between Jatropha and castor bean. Transcriptomic analysis of female and male flowers revealed the up-regulation of a dozen family of TFs in female flower. Additionally, we constructed a robust species tree enabling estimation of divergence times among nine Jatropha species and five commercial crops in Malpighiales order. Our results will help researchers and breeders increase energy efficiency of this important oil seed crop by improving yield and oil content, and eliminating toxic compound in seed cake for animal feed.

Seed storability is especially important in the tropics due to high temperature and relative humidity of storage environment that cause rapid deterioration of seeds in storage. The objective of this study was to use SSR markers to identify genomic regions associated with quantitative trait loci (QTLs) controlling seed storability based on relative germination rate in the F2:3 population derived from a cross between vegetable soybean line (MJ0004-6) with poor longevity and landrace cultivar from Myanmar (R18500) with good longevity. The F2:4 seeds harvested in 2011 and 2012 were used to investigate seed storability. The F2 population was genotyped with 148 markers and the genetic map consisted of 128 SSR loci which converged into 38 linkage groups covering 1664.3 cM of soybean genome. Single marker analysis revealed that 13 markers from six linkage groups (C1, D2, E, F, J and L) were associated with seed storability. Composite interval mapping identified a total of three QTLs on linkage groups C1, F and L with phenotypic variance explained ranging from 8.79 to 13.43%. The R18500 alleles increased seed storability at all of the detected QTLs. No common QTLs were found for storability of seeds harvested in 2011 and 2012. This study agreed with previous reports in other crops that genotype by environment interaction plays an important role in expression of seed storability.

Genetic variation in Jatropha curcas, a prospective biodiesel plant, is limited, and interspecific hybridization needed for its genetic improvement. Progeny from interspecific crosses between J. curcas and Jatropha integerrima can be used to improve agronomic characters and to increase oil content and yield. However, these hybrids have not been characterized cytologically. The present study was aimed at the analysis of chromosome behavior during meiosis and chromosome composition of S1 plants derived from an interspecific F1 hybrid using genomic in situ hybridization (GISH) and fluorescence in situ hybridization (FISH). Bivalents that formed as a result of interspecific pairing were frequently observed, suggesting the presence of homoeologous chromosomes from the two species. Almost half of microspores were derived from the reduction division; GISH analysis indicated random transmission of the parent chromosomes to microspores. Male fertility measured as pollen staining with acetocarmine was 48.4%. In contrast, GISH analysis of S1 plants revealed preferential transmission of J. curcas chromosomes. We also found segment exchange between chromosomes of the two species (interspecific translocation) by GISH and FISH analyses. Introgression of J. integerrima chromosome segments into the J. curcas genome would help to improve Jatropha cultivars for mass production.