Plastid trnL intron polymorphisms among Phalaenopsis species used for identifying the plastid genome type of Phalaenopsis hybrids

The trnL intron sequences of plastid DNA for over 95% of the living native species of Phalaenopsis were determined in this study, and nearly all Phalaenopsis species were found to bear unique trnL intron sequences resulting from mutations, insertions/deletions, or both. These trnL intron sequences have been deposited into GenBank database for further identifying the plastid genome type of Phalaenopsis hybrids. Molecular evidence has demonstrated that maternal inheritance of the plastid genome occurs during interspecific hybridization of Phalaenopsis species. Therefore, the plastid genome type of Phalaenopsis hybrids can be determined by comparing the trnL intron sequences of the hybrids to GenBank database. The plastid genome type of the hybrids that is revealed through this analysis can be used to re-evaluate their genealogies because plastid DNA is maternally inherited. We examined trnL intron sequences from three Phalaenopsis hybrids including P. Yungho Gelb Canary, P. Timonthy Christopher, and P. Rainbow Chip to re-evaluate their genealogies from the recording of the Sander's List of Orchid Hybrids. No heterogeneous trnL intron sequences were found for any of the Phalaenopsis hybrids examined. After sequence comparing to GenBank database, the plastid genome types of the hybrids are determined. The conflict of genealogy and the plastid genome type in two hybrids P. Timonthy Christopher and P. Rainbow Chip can be found. This conflict results from their female parent P. Cassandra with wrong registration in Sander's List of Orchid Hybrids at Royal Horticultural Society (RHS).

► The trnL intron sequences of plastid DNA for most of the living native Phalaenopsis species were determined.
► The trnL intron sequences of different Phalaenopsis species are unique.
► We have developed an approach to identify the plastid genome type of Phalaenopsis hybrids.