Production of Hybrids Between the 2EBN Bridge Species Solanum verrucosum and 1EBN diploid Potato Species

The potato crop has diploid wild relatives in the primitive 1EBN crossability group that have a wealth of desirable traits, but are currently difficult to access through conventional crossing. The objective of this study was to develop an efficient technique for using 1EBN species in breeding by crossing to 2EBN bridge species S. verrucosum. Success was obtained with several 1EBN diploid species: S. bulbocastanum, S. pinnatisectum, S. polyadenium, S. commersonii and S. circaeifolium. Use of 2x(2EBN) S. verrucosum as a receptive female avoided prezygotic interspecific incompatibility, and double rescue pollination was done using haploid-inducing clone, S. phureja IvP35 to minimize postzygotic failure due to abortion of berries with few or small seeds. In total, 4,646 hybrid seeds were obtained in crosses between S. verrucosum and the 1EBN species. Rescue pollination particularly improved seeds per pollination for S. pinnatisectum hybrids. The hybrid seeds were normal in appearance and had high germination (47-88 %). They produced plants with the distinctive phenotypic characteristics and molecular markers specific to their 1EBN parents. Hybrids had poor male fertility, but crossed easily as females to diploid S. tuberosum at an average of 38 seeds per pollination.