title: Genetic features of the spontaneous self-compatible mutant, 'Jin Zhui' (Pyrus bretschneideri Rehd.).
abstract: 'Jin Zhui' is a spontaneous self-compatible mutant of 'Ya Li' (Pyrus bretschneideri Rehd. S21S34 ), the latter displaying a typical S-RNase-based gametophytic self-incompatibility (GSI). The pollen-part mutation (PPM) of 'Jin Zhui' might be due to a natural mutation in the pollen-S gene (S34 haplotype). However, the molecular mechanisms behind these phenotypic changes are still unclear. In this study, we identified five SLF (S-Locus F-box) genes in 'Ya Li', while no nucleotide differences were found in the SLF genes of 'Jin Zhui'. Further genetic analysis by S-RNase PCR-typing of selfed progeny of 'Jin Zhui' and 'Ya Li' × 'Jin Zhui' progeny showed three progeny classes (S21S21 , S21S34 and S34S34 ) as opposed to the two classes reported previously (S21S34 and S34S34 ), indicating that the pollen gametes of 'Jin Zhui', bearing either the S21 - or S34 -haplotype, were able to overcome self-incompatibility (SI) barriers. Moreover, no evidence of pollen-S duplication was found. These findings support the hypothesis that loss of function of S-locus unlinked PPM expressed in pollen leads to SI breakdown in 'Jin Zhui', rather than natural mutation in the pollen-S gene (S34 haplotype). Furthermore, abnormal meiosis was observed in a number of pollen mother cells (PMCs) in 'Jin Zhui', but not in 'Ya Li'. These and other interesting findings are discussed.
authors.affiliation: Laboratory of Fruit Tree Cell and Molecular Breeding, China Agricultural University, Beijing, China.
authors.forename: Junkai
authors.initials: J
authors.lastname: Wu
authors.forename: Maofu
authors.initials: M
authors.lastname: Li
authors.forename: Tianzhong
authors.initials: T
authors.lastname: Li
mesh_terms: D032461:Chromosomes, Plant / Q000235:genetics; D016000:Cluster Analysis; D044783:F-Box Proteins / Q000145:classification / Q000235:genetics; D035264:Flowers / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D006239:Haplotypes; D008540:Meiosis / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D010940:Plant Proteins / Q000145:classification / Q000235:genetics; D011058:Pollen / Q000235:genetics*; D054817:Pollination / Q000235:genetics; D031989:Pyrus / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D060436:Self-Incompatibility in Flowering Plants / Q000235:genetics*
chemical_list: D044783:F-Box Proteins; D010940:Plant Proteins