ARS | Publication request: Modified Conventional Breeding Methods to Efficiently Transfer Unique Late Blight Resistance from 2x(1ebn) Mexican Species to 2x(2ebn) and 4x(4ebn) Breeding Lines.

Submitted to: American Journal of Potato Research
Publication Type: Abstract Only
Publication Acceptance Date: April 20, 2001
Publication Date: N/A

Technical Abstract: Several 2x(IEBN) Mexican species exhibit extreme late blight resistance, but have not been used in breeding because they do not readily cross with haploids or common cultivars due to EBN differences. Two methods have been developed using sexual hybridization to transfer germplasin from 2x(IEBN) species to the 2x(2EBN) and 4x(4EBN) levels. One uses double pollination techniques coupled with embryo rescue and has resulted in the formation of a S. pinnatisectum-Tuberosum haploid hybrid. This hybrid, though male sterile, has been successfully crossed as a female to 2x(2EBN) S. chacoense, S. phureja, S. sparispilum, and a 4x(4EBN) cultivar. A second method uses the Mexican species,2x(2EBN) S. verrucosum, as a bridge species with 2x(IEBN) species. The 2x(I 1/2EBN) hybrids should segregate for EBN and therefore be crossable to 2x(IEBN) and 2x(2EBN) lines as well as to 4x(4EBN) parental material, if 2n gametes function. The 2x(I 1/2EBN) hybrids have been successfully crossed with 2x(2EBN) S. chacoense, S. phureja and Tuberosum haploids; with 2x(IEBN) S. conumrsonii, S. pinnatisectum and S. trifidum, and with a 4x(4EBN) cultivar. The derived hybrids have been crossed extensively with haploids and cultivars. We have demonstrated two modified conventional breeding methods to successfully transfer this resistance to the 2x(2EBN) or 4x(4EBN) level.