Genetic relationships among two Perilla crops, shiso [Perilla sp.] and egoma [Perilla frutescens], and the weedy type revealed by RAPD markers

Two distinct crops of Perilla frutescens Britt. (Labiatae), leafy vegetable (var. crispa, shiso in Japanese) and oil crop (var. frutescens, egoma in Japanese) and the weedy type were investigated to clarify their genetic relationships. Twenty-five samples from Japan were analyzed by the RAPD technique with 40 random decamer primers and a phenogram was constructed based on RAPD using the neighbor joining method. Among 284 different bands detected, 124 (44%) showed polymorphisms. The weedy type Perilla was most variable with 76 (27%) polymorphic bands compared to 67 (24%) of var. crispa and 62 (23%) of var. frutescens. The weedy Perilla had only four unique bands, while var. crispa and var. frutescens had 13 and 14 unique bands, respectively. In the phenogram, var. crispa and var. frutescens each formed a cluster, whereas different samples of the weedy type occupied different positions in the tree. This implies that gene flow between the two crops is limited although they are artificially crossable with each other. The position of the samples of var. crispa and var. frutescens in the phenogram has no relationship with the geographical locations of the samples. Four out of six samples of the weedy type were situated on the branches connecting the crispa and frutescens groups in the phenogram. This may suggest that these samples originated from hybrids between var. crispa and var. frutescens.