A cellulose binding domain protein restores female fertility when expressed in transgenic Bintje potato

BACKGROUND: Expression of a gene encoding the family 1 cellulose binding domain protein CBD1, identified in the cellulosic cell wall of the potato late blight pathogen Phytophthora infestans, was tested in transgenic potato to determine if it had an influence on plant cell walls and resistance to late blight. RESULTS: Multiple regenerants of potato (cv. Bintje) were developed and selected for high expression of CBD 1 transcripts. Tests with detached leaflets showed no evidence of increased or decreased resistance to P. infestans, in comparison with the blight susceptible Bintje controls, however, changes in plant morphology were evident in CBD 1 transgenics. Plant height increases were evident, and most importantly, the ability to produce seed berries from a previously sterile cultivar. Immunolocalization of CBD 1 in seed berries revealed the presence throughout the tissue. While Bintje control plants are male and female sterile, CBD 1 transgenics were female fertile. Crosses made using pollen from the late blight resistant Sarpo Mira and transgenic CBD1 Bintje as the female parent demonstrated the ability to introgress P. infestans targeted resistance genes, as well as genes responsible for color and tuber shape, into Bintje germplasm. CONCLUSIONS: A family 1 cellulose-binding domain (CBD 1) encoding gene from the potato late blight pathogen P. infestans was used to develop transgenic Bintje potato plants. Transgenic plants became female fertile, allowing for a previously sterile cultivar to be used in breeding improvement. Selection for the absence of the CBD transgene in progeny should allow for immediate use of a genetically enhanced material. Potential for use in other Solanaceous crops is proposed.