Abstract
To clarify the main causes affecting the mode of plastid DNA (ptDNA) inheritance in Rhododendron spp., ptDNA inheritance of progenies from diallel crosses among six evergreen azalea species belonging to series Kaempferia was investigated with PCR-SSCP analysis. Polymorphism was detected among parental species, except one combination between R. kiusianum and R. tosaense. Maternal ptDNA inheritance was observed in all crosses, whereas paternal inheritance was found in 16/28 crosses. High frequency (33.3 to 87.5%) of paternal ptDNA inheritance was observed in all crosses with R. transiens as a seed parent, whereas the frequency was relatively low (less than 8.3%) in the reverse cross, except R. tosaense × R. transiens. In contrast, no or slight (less than 12.5%) paternal ptDNA inheritance was observed in the cross with R. kaempferi var. macrogemma, R. kiusianum and R. simsii as a seed parent. When these species were used as pollen parents in the cross with other three species, i.e. R. transiens, R. kaempferi and R. tosaense, the frequency was usually high (45.0 to 90.9%, except R. kaempferi × R. kaempferi var. macrogemma).
