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.