Seed size is one of the most important traits in leguminous crops. We obtained a recessive mutant of blackgram that had greatly enlarged leaves, stems and seeds. The mutant produced 100% bigger leaves, 50% more biomass and 70% larger seeds though it produced 40% less number of seeds. We designated the mutant as multiple-organ-gigantism (mog) and found the mog phenotype was due to increase in cell numbers but not in cell size. We also found the mog mutant showed a rippled leaf (rl) phenotype, which was probably caused by a pleiotropic effect of the mutation. We performed a map-based cloning and successfully identified an 8 bp deletion in the coding sequence of VmPPD gene, an orthologue of Arabidopsis PEAPOD (PPD) that regulates arrest of cell divisions in meristematic cells. We found no other mutations in the neighboring genes between the mutant and the wild type. We also knocked down GmPPD genes and reproduced both the mog and rl phenotypes in soybean. Controlling PPD genes to produce the mog phenotype is highly valuable for breeding since larger seed size could directly increase the commercial values of grain legumes.

A mungbean (V. radiata) line (BC3F3 generation) which is resistant to two species of bmchid beetles (Callosobruchus chinensis and C. maculatus) was successfully developed in Thailand using a wild mungbean variety (V. radiata var. sublobata). One accession (TCI966) of wild mungbean was found to be completely resistant to C. chinensis and C maculatus occurring at Chainat Field Crops Research Center in Thailand. The resistance was controlled by a single dominant gene {R). A breeding program to develop a bruchid-resistant mungbean cultivar with good agronomic characters under the environmental conditions of Thailand was initiated in 1987. 'Chainat 60' ('CN60'), a recommended mungbean cultivar in Thailand, was crossed with TC1966 to incorporate the resistance gene. Agronomic characters of the hybrids were improved by recurrent backcrossing using 'CN60' as a pollen parent. Seed yield per plant, days to flowering, and seed size of the bruchid-resistant BC3F2 population reached the level of 'CN60' after three consecutive backcrossings. Bruchid-resistant line (BC3F3, R/R) was selected from individual BC3F2 plants.

Seed protein of 581 local strains of mung bean, Vigna radiata (L.) Wilczek, collected from throughout Asia, were analyzed by SDS-polyacrylamide gel electrophoresis. Eight protein types were recognized based on the combination of four albumin bands and three globulin bands. The frequency of each protein type strain showed a clear geographical cline. The pattern of geographical distribution of the protein types reflected the regions of genetic diversity, and two dissemination pathways in mung bean were proposed. The region of genetic diversity in seed protein was western Asia (Afghanistan-Iran-Iraq area). Mung bean may have spread mainly to the east by two routes from India, where the domestication of mung bean is believed to have occurred. One route led to Southeast Asia; strains consisting of a few protein types with prominent protein type 1 were disseminated from India to the Southeast Asian countreis. Thus, the strain composition in Southeast Asia was very simple, with the strains being similar to one another. Another dissemination pathway may have been the route known as the Silk Road. Since protein type 7 and 8 strains could not be found throughout Southeast Asia, it is assumed that these strains spread from western Asia or India to China and Taiwan via the Silk Road, and not by the route from Southeast Asia.

No abstract