Summary Lotus is a leguminous and cosmopolitan genus in the Loteae tribe consisting of more than 200 species. The number of chromosomes has been reported for many Lotus species; however, molecular studies have focused only on a few important species of this genus. The present study was conducted to estimate the genome size and ploidy levels of 28 Lotus accessions, and to identify their genetic diversity using inter-simple sequence repeat (ISSR) analysis. The chromosome number of 16 accessions agreed with previous reports (except for Lotus salsuginosus), while that in 11 accessions were reported here for the first time. The smallest nuclear DNA content was identified in the diploid, Lotus unifoliolatus (0.28 0.01 pg C 1 ). In contrast, the tetraploid, Lotus australis, had a genome size of 1.28 0.03 pg C 1 , representing a five-fold difference in genome size among the Lotus species. When expressed as a per Cx value, Lotus species genome sizes ranged from 0.28 pg Cx 1 in L. unifoliolatus to 0.71 pg Cx 1 in Lotus wrightii, representing a 2.5-fold difference. There was no relationship between genome size and chromosome number or ploidy level; thus, genome size is species specific in the Lotus species. On ISSR analysis, a total of 379 fragments were generated with 12 primers, and all accessions were grouped into four clusters by phylogenetic analysis. The results of this investigation will be useful for plant breeders attempting to expand the genetic variation found in this species by crossbreeding using these resources.

Wild soybean (Glycine soja) is a valuable genetic resource for soybean improvement. Seed composition profiles provide beneficial information for the effective conservation and utilization of wild soybeans. Therefore, this study aimed to assess the variation in free amino acid abundance in the seeds of wild soybean germplasm collected in Japan. The free amino acid content in the seeds from 316 accessions of wild soybean ranged from 0.965 to 5.987 mg/g seed dry weight (DW), representing a 6.2-fold difference. Three amino acids had the highest coefficient of variation (CV): asparagine (1.15), histidine (0.95) and glutamine (0.94). Arginine (0.775 mg/g DW) was the predominant amino acid in wild soybean seeds, whereas the least abundant seed amino acid was glutamine (0.008 mg/g DW). A correlation network revealed significant positive relationships among most amino acids. Wild soybean seeds from different regions of origin had significantly different levels of several amino acids. In addition, a significant correlation between latitude and longitude of the collection sites and the total free amino acid content of seeds was observed. Our study reports diverse phenotypic data on the free amino acid content in seeds of wild soybean resources collected from throughout Japan. This information will be useful in conservation programmes for Japanese wild soybean and for the selection of accessions with favourable characteristics in future legume crop improvement efforts.