Genetics of self-compatibility in a self-incompatible wild diploid potato species Solanum chacoense. 2. Localization of an S locus inhibitor (Sli) gene on the potato genome using DNA markers

A self-compatible (SC) hybrid plant F₁-1 was obtained from a cross between a SC variant of a wild diploid potato species, Solanum chacoense, and a self-incompatible (SI) cultivated diploid species, S. phureja. The clone F₁-1 has previously been proposed to have a dominant S locus inhibitor gene (Sli) in a heterozygous condition. It was crossed as a male parent with a selected clone from a S. stenotomum-S. phureja population, resulting in a segregating population consisting of 116 hybrid plants. Self-compatibility was assessed by selfing each of the hybrids. Sixty-six of them were SC, while 35 were SI, showing a significant distortion from an expected Mendelian ratio of 1:1. A genetic linkage map was constructed using DNA markers to localize the Sli gene. A total of 28 RAPD and 127 RFLP markers identified 109 mapping positions on 12 linkage groups. The Sli gene was mapped at a distal end of chromosome 12. Since the S locus has been localized on chromosome 1 on the potato RFLP map, it is confirmed that the Sli gene is independent of the S locus. This revised version was published online in August 2006 with corrections to the Cover Date.