Abstract
The natural populations of Rhododendron ripense Makino distributed in the San-in and Shikoku area, Japan, were investigated for the application in breeding materials. Genetic diversity was evaluated based on their morphological characters and chloroplast DNA polymorphism. Wild habitats of R. ripense in the San-in area have been considered to be disturbed by construction of dams and river improvements compared to vegetation of about 40 years ago. R. ripense in the San-in area have flower corolla of approximately 6 cm diameter and showed local morphological diversity in corolla broche and sepal length. They tended to have bigger corolla diameter, deeper broche color and wider leaves than flowers of the Shikoku area. On principal component analysis, the first and second principal component had a high contribution ratio in morphological characteristics of flower and leaf. In the scatter diagram of distribution, the main San-in river populations were distributed closely, whereas the west San-in and Shikoku river populations were distributed beyond these areas. The sequence mutation that indicates local genetic diversity was detected in intron of trnW-trnP on chloroplast DNA. The populations in the San-in river area have mainly TA sequence type, whereas those of the Shikoku river area showed both TA and AT sequence types.
