Abstract
Naturalized white clover (Trifolium repens) is now widely distributed throughout Japan, from Hokkaido to Okinawa Prefecture in latitude and from almost Om to more than 1,000m in altitude. The objective of this paper is to describe the latitudinal variation in cyanogenesis in Japan and the altitudinal variation in cyanogenesis at Mt. Fuji. Cyanogenesis was examined with a sodium picrate test for 14 natural populations with different latitudes and 4 natural populations with different altitudes along the road at Mt. Fuji. The results confirmed a latitudinal variation in AcLi (the phenotype releasing HCN) frequency with the similar pattern to that well known in Europe ; the northern populations such as those from Hokkaido and Tohoku District showed lower frequencies of AcLi than the southern populations. Further analysis of variation in cyanogenesis among the southern populations showed a complex pattern, suggesting that there is no consistent trend related to their latitudes in the southern part of Japan. The result for the populations of Mt. Fuji indicated the presence of altitudinal cline for cyanogenesis; lower-altitudinal populations had higher frequencies of AcLi than higher-altitudinal ones. It was considered that this variation pattern was formed approximately within 30 years. Agronomic implications of AcLi are also discussed.
