Identification and Characterization of S-RNases in Japanese Plum Genotypes

Many species of the genus Prunus exhibit the gametophytic self-incompatibility system, governed by the S-locus, that encode S-Ribonucleases in the pistil, and are able to degrade the RNA of the pollen tubes when the S-haplotypes of both gametophytes are the same, preventing the fertilization of the oosphere. The objective of this study was to identify and characterize the S-alleles of Japanese Plum genotypes to verify groups of reproductive compatibility. Isolation, amplification and DNA sequencing were performed to obtain an allelic profile of the genotypes. Combinations of PC1 and PC2 primers identified 95% of the genotypes. After sequencing, the 'Sc', 'Si', 'Sa' and 'Sh' alleles were obtained with an identity greater than 90%, compared to the NCBI sequences. PC2 was more extensive in identifying the S-alleles in the S-RNases coding region, generating larger fragments than PC1. In this way, it was possible to generate three groups of genotypes with S-alleles of the same size with PC2: Group 1 (Selection Embrapa A19, Selection Embrapa A28, Black Amber Black, Fortune, Roysum, SC-7 and Zafira); and Group 2: (Selection Embrapa A7, Carazinho, Sanguínea, Laroda, SC-15 and Rebelatto) and Group 3 (Selection Ameixa 86-13, Golden King, Letícia and Robusto). Each primer combination amplified only one allele per genotype, suggesting the development of specific primers to amplify the S-alleles in each genotype. The identification and characterization of the alleles allow the use of genotypes compatible with each other, considering the floral synchrony of the genotypes, besides providing information for the management of the breeding processes in Japanese Plums.