Identification of new S-RNase self-incompatibility alleles and characterization of natural mutations in Iranian almond cultivars

The two main objectives of this research were to identify new S-RNase alleles in Iranian almond cultivars and to characterize naturally occurring mutations in these alleles that may cause self-compatibility. We investigated S genotypes of 22 Iranian almond cultivars using stylar RNase electrophoresis, PCR and DNA sequencing. We report six previously unidentified P. dulcisS-RNase alleles (S45, S46, S47, S48, S49 and S50). Four of 12 tested S-RNases were found to be non-functional in vitro: S49, S50, S24/Sna and S25/S47. Detected point mutations in the C3 coding region of S49- and S50-RNase, leading to the replacement of a highly conserved cysteine and histidine residues, are with the highest probability the reason of these S-RNases inactivity. Results also suggested that ten Iranian almond cultivars display unique S genotype. All presented data confirm Iranian cultivars as valuable almond sources which are of interest to almond breeding and conservation programs.