Molecular diversity of three S-allele cDNAs associated with gametophytic self-incompatibility in Lycopersicon peruvianum.

We isolated S allele-associated cDNA clones from each of the stylar cDNA libraries of Lycopersicon peruvianum of two different S genotypes (S12Sb and S13Sc) with S11Sa allele-associated cDNA (LPS11) as a probe. The longest cDNA clones, designated LPS12 and LPS13, which were 779 bp and 853 bp in length, contained open reading frames of 189 and 210 amino acids, respectively. The three S allele-associated cDNAs (LPS11, LPS12, and LPS13) did not cross-hybridize to each other under highly stringent condition by northern blot analysis. Their average identity to Nicotiana alata S-proteins so far was 49%. The fragments corresponding to LPS11 or LPS12 cosegregated with their respective S alleles in genetic crosses. From these results, we conclude that the three cloned cDNAs were derived from the three different S alleles of L. peruvianum.