BackgroundSegregation distortion (SD) is a frequently observed occurrence in mapping populations generated from crosses involving divergent genotypes. In the present study, ten genetic linkage maps constructed from reciprocal F2 and BC1F1 mapping populations derived from the parents Dasanbyeo (indica) and Ilpumbyeo (japonica) were used to identify the distribution, effect, and magnitude of the genetic factors underlying the mechanisms of SD between the two subspecies.ResultsSD loci detected in the present study were affected by male function, female function, and zygotic selection. The most pronounced SD loci were mapped to chromosome 3 (transmitted through male gametes), chromosome 5 (transmitted through male gametes), and chromosome 6 (transmitted through female gametes). The level of SD in BC1F1 populations which defined by chi-square value independence multiple tests was relatively low in comparison to F2 populations. Dasanbyeo alleles were transmitted at a higher frequency in both F2 and BC1F1 populations, suggesting that indic a alleles are strongly favored in inter-subspecific crosses in rice. SD loci in the present study corresponded to previously reported loci for reproductive barriers. In addition, new SD loci were detected on chromosomes 2 and 12.ConclusionThe identification of the distribution of SD and the effect of genetic factors causing SD in genetic mapping populations provides an opportunity to survey the whole genome for new SD loci and their relationships to reproductive barriers. This provides a basis for future research on the elucidation of the genetic mechanisms underlying SD in rice, and will be useful in molecular breeding programs.Electronic supplementary materialThe online version of this article (doi:10.1186/s12284-014-0003-8) contains supplementary material, which is available to authorized users.

Despite widespread mungbean [Vigna radiata (L.) Wilczek] consumption in Indonesia, few molecular studies have been carried out on accessions and available data are minimal. In this study, we used 30 newly developed simple sequence repeat (SSR) markers designed from the mapped sequence scaffolds of the Korean Sunhwanokdu and Gyeonggijaerae 5 mungbean genomes. These markers were used to examine loci in 83 mungbean accessions collected from diverse geographical areas in Indonesia. A total of 107 alleles were detected among the accessions with 29 polymorphic markers. However, the mean of polymorphic information content (0.33) value and diversity index (0.38) value was indicative of low genetic diversity in this germplasm. The mungbean population structure was not clearly differentiated and the number of subpopulations was unclear. Neighbour-joining tree analysis revealed that the genetic cluster did not reflect the geographical origin of the accessions. Interestingly, the most agriculturally improved varieties were genetically similar to some landraces from one of the main mungbean-producing regions. These newly developed SSR markers could be useful for detecting genetic variability as a basis for establishing a conservation strategy for mungbean germplasm with the aim of enhancing Indonesian breeding programmes.

Rice sucrose synthase 3 (RSUS3) is expressed predominantly in rice seed endosperm and is thought to play an important role in starch filling during the milky stage of rice seed ripening. Because the genetic diversity of this locus is not known yet, the full sequence of RSUS3 from 43 rice varieties was amplified to examine the distribution of DNA polymorphisms. A total of 254 sequence variants, including SNPs and insertion/deletions, were successfully identified in the 7733 bp sequence that comprises the promoter, exons and introns, and 3' downstream nontranscribed region (NTR). Eleven haplotypes were distinguished among the 43 rice varieties based on nucleotide variation in the 3 defined regions (5' NTR, transcript, and 3' NTR). The promoter region showed evidence of a base change on a cis-element that might influence the functional role of the motif in seed-specific expression. The genetic diversity of the RSUS3 gene sequences in the rice germplasm used in this study appears to be the result of nonrandom processes. Analysis of polymorphism sites indicated that at least 11 recombinations have occurred, primarily in the transcribed region. This finding provides insight into the development of a cladistic approach for establishing future genetic association studies of the RSUS3 locus.