XVI International Botanical Congess

Pinus species exhibit a paternal cpDNA inheritance and a maternal mtDNA inheritance. The levels and patterns of cpDNA and mtDNA introgression between the two pine species, P. pumila and P. parviflora var. pentaphylla, were examined by PCR-based genetic markers. The survey demonstrated a generality in the uni-directional pattern of cytoplasmic gene flow between the two pine species, i.e. paternal cpDNA flowed from P. parviflora var. pentaphylla to P. pumila, and in contrast, maternal mtDNA flowed from P. pumila to P. parviflora var. pentaphylla. Whenever plants which had a non-native combination of cpDNA and mtDNA were observed, they always had the cpDNA of P. parviflora var. pentaphylla and the mtDNA of P. pumila. The existence of only this type of cytoplasmic chimera may suggest unilateral cross incompatibility between the two pine species.