Polyacrylamide gel electrophoresis of S-RNase fragments for identification of S -genotypes of Japanese pear ( Pyrus pyrifolia )

摘要

Japanese pear ( Pyrus pyrifolia ) exhibits gametophytic self-incompatibility (GSI) controlled by a complex and multiallelic S locus. The pistil-part product of the S locus is the polymorphic ribonuclease, S-RNase. Information on S -genotypes is important for the production and breeding of Japanese pears. Molecular analyses of S -genotypes of Japanese pear have been conducted with the CAPS (cleaved amplified polymorphic sequence) system; PCR amplification of S-RNase fragments by a common primer pair followed by digestion with restriction enzymes each of which cleaves a specific S haplotype. Here, we show that the separation of S-RNase fragments by polyacrylamide gel electrophoresis (PAGE) distinguishes four out of nine S haplotypes of Japanese pear without restriction digestion. S 3-, S 5-, S 6- and S 8- RNase s were identified as distinct bands by PAGE. S 3- and S 5- RNase s were separated by PAGE despite their identical fragment sizes. Using this system, three Japanese pear lines with unknown S -genotypes were analyzed. The newly determined S -genotypes of the lines were confirmed by CAPS analysis.