RFLP and inheritance patterns of chloroplast DNA in intergeneric hybrids of Phalaenopsis and Doritis

The mode of inheritance of chloroplasts was analyzed using restriction fragment length polymorphism (RFLP) in both interspecific hybrids of Phalaenopsis and intergeneric hybrids of Phalaenopsis and Doritis. Chloroplast DNA digested with Dra I followed by hybridization with an rbcL probe revealed that Phalaenopsis amabilis, Phalaenopsis aphrodite, and Phalaenopsis stuartiana, which belong to the taxonomic section PHALAENOPSIS, have the same size 2.0-kb fragment. Both Phalaenopsis mannii and Phalaenopsis amboinensis have a 2.3-kb fragment, while Doritis pulcherrima has a 3.5-kb fragment. In both interspecific and intergeneric hybrids, maternal inheritance of the chloroplast genome was detected. The hybrids of both reciprocal crosses (A x B and B x A) are registered with the same hybrid names in Sander's List of Orchid Hybrids at the Royal Horticultural Society, despite harboring chloroplast DNA from different parents. These results suggest that the chloroplast DNA can be used as a marker for identification of parentship and for phylogenetic studies of taxonomy.