THE ROLE OF PREZYGOTIC SELF-COMPATIBILITY IN FACILITATING INTERSPECIFIC COMPATIBILITY IN SOLANUM SECTION PETOTA

Domesticated potato (Solanum tuberosum L.) is the fourth most important food crop worldwide and critical food security crop. The high significance of this crop coupled with high production losses place potato at a high priority for genetic improvement, especially in the face of climate change. Potato breeding is undergoing a seismic shift from a tetraploid outcrossing crop towards a F1 hybrid system using diploid inbred lines as parents. This transformation has also changed how potato breeders access important traits from wild species. Pre- and post-zygotic barriers, such as self-incompatibility (SI) and endosperm failure, inhibit and complicate the use of the more valuable wild species in conventional and diploid breeding schemes. Traditionally plant breeders have employed the SC x SI rule, using self-compatibility (SC) to increase the success of interspecific crosses. In order to evaluate the potential of several different SC factors in facilitating broad interspecific compatibility: Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas9 knockout (KO) lines of S-RNase, HT-B and HT-B + S-RNase in S. tuberosum were evaluated along with the self-compatible species S. verrucosum, and S-locus inhibitor gene (Sli) from S. chacoense. Findings confirm the central role of S-RNase in interspecific pollination barriers and the inconsequential role of HT-B alone. Sli had no effect on interspecific barriers despite its prominent role as a source of SC. Finally, S. verrucosum styles displayed an absence of prezygotic barriers. Further analysis of the role of HT-A, as well as other mechanisms that potentially underlie the SC phenotype in S. verrucosum will further clarify the role of specific genetic factors that regulate interspecific compatibility in Solanum section Petota