Crossability of a high-mountain dwarf variety of Lysimachia japonica (Primulaceae) endemic to Yakushima Island with its normal-sized lowland counterpart

A high-mountain dwarf plant of Lysimachia japonica (Primulaceae) endemic to Yakushima is reported to be very unique in the dwarfing mechanism at cell level, and the plant is one of the candidates to be a key species to reveal the unsolved molecular mechanism of taxon-specific body size of plant. In the present study, we examined the crossability between the dwarf plant of L. japonica and its normal-sized lowland counterpart, and self- and cross-compatibilities within each linage. The results indicate that both dwarfed and normal-sized L. japonica are self- and cross-compatible within each ecotype and are bidirectionally cross-compatible with each other, suggesting that this plant possesses optimum life historical traits for further genetic analysis in order to clarify the mystery of molecular mechanism of taxon-specific body size.