Identification of new S-Rnase alleles and s-genotype in two pear species (Pyrus pyrifolia and P. bretschneideri) grown in China by genomic pcr and pollination tests

Abstract

Most of the economically important Chinese pears display S-RNase-based gametophytic self-incompatibility (GSI). By genomic PCR and sequence analysis, five new S-RNase alleles (S5a and S 11 to S 14) in three Chinese sand pear (Pyrus pyrifolia) cultivars and six (S a to S f) in five Chinese white pear (P. bretschneideri) cultivars were identified. Comparison of nucleotide sequences of S-RNase alleles from the two different Chinese pear species revealed that S a, S b, and S d of P. bretschneideri was identical to S 8, S 14, and S12 of P. pyrifolia, respectively. We obtained the full-length cDNA sequence of S 12 and determined S 12 was expressed only in the style of pear. The functions of the new S-RNase alleles were confirmed by the controlled pollination tests. As the results, the eight cultivars of the two Chinese pear species were genotyped as: ‘Maogong’ (S 11 S 12), ’Cangxixueli’ (S 5a S 13), ‘Guiguan’ (S 2 S 14), ‘Jinfeng’ (S a S b), ’Matihuang’ (S b S c), ‘Jinhuasihao’ (S d S e), ’Youli’ (S b S c), and ‘Jitui’ (ScS f). Elucidation of S-genotype would contribute to higher and stable yields in the orchards and a more efficient breeding programme of pears. © 2007 Taylor & Francis Group, LLC.