Molecular Mechanism Of Self-Compatibility In Peach And’zaosu’

Pear and peach were used as materials. Based on their self-compatibility, stylar and pollen S alleles and some of the S-genotypes were identified. The results are as follows:1. Take the ’Yulu’、’Datuan’ as test materials, using pairs of primers specific to peach S-RNase gene of style and gene SFB of pollen, PCR amplification from genomic DNAs of three peach cultivars were carried out. Then the PCR products were extracted, cloned and sequenced. The amplified fragments were assigned to their respective S-RNases by blast analysis. Finally to identify the S-genotypes of the three tested self-compatible cultivars. The S-RNase genotype of ’Yulu’ are S1S2(m) and SFB1SFB2, And ’Datuan’ contains onlyS2(m)、SFB2.The identification results of S-RNase genes and SFB gene showed that both the S genotypes of ’Yulu and Datuan’ in hybrids and the S genotypes of them in selfing generations follows the Mendelian laws of distribution. The hybrids varieties S-genotype of Yulu and Datuan’ are "S1S2(m) or S2(m)S2(m)"and the hybrids varieties S-genotype of ’Yulu and Datuan’ are "SFB1SFB2or SFB2SFB2".2. PCR were performed with specific primer sets of Prunus S-RNase and SFB alleles using ’Zhongyou5’ as the template. The amplification products were extracted, cloned, sequenced and then Blast analysis, which were used to determine the S-genotype of this cultivar, S1S2(m). Sequence analysis showed that Prunus persica S1-RNase and S2(m)-RNase alleles have exceptionally high identities with other Prunus S-RNase alleles, which indicate that Prunus S-RNase diverged before the divergence of species. Similarly, Prunus persica SFB1and SFB2alleles have exceptionally high identities with other Prunus SFB alleles, which indicate that Prunus SFB diverged before the divergence of species, too. The S-genotypes of self-pollinated progeny of ’Zhongyou5’ were detected, it is obviously that three classes were found in progeny, and the segregation ratio of S1S2, S1S2(m)and S2(m)S2(m) was8:13:7, which did fit to the expected ratio that was1:2:1(χ2=0.214<χ20.05,2=5.991). This result showed that S-RNase and SFB alleles are tightly co-segregation according to the Mendel genetic model. Moreover, the existence of S1S1and S2(m)S2(m)homozygotes suggested that SFB1and SFB2could not be cognized by self S-RNase, due to that the protein of these two SFB alleles were premature, which resulted in the peach cultivars containing these two SFB alleles are self-compatible.3Pear is a typical fruit tree of gametophytic self-incompatibility (GSI). This characteristic results in low yield under the condition of natural pollination, so it is necessary to arrange varieties for pollination or to perform artificial pollination toincrease the yield. Using a pair of primers specific to pear S-RNases, PCR amplification of S genes fromgenomic DNA of ten pear cultivars was carried out. Then the PCR products were extracted, cloned and sequenced. The amplified fragments were assigned to their respective S-RNases by Blast analyses. The S-genotypes of the ten tested pear cultivars were identified as follows:Pingguoli (S1Sdm); Huasu (S5Sd); Shenbuzhi (S5Sd); Zaosu (S1Sd); Zhongli1(S4S17); Huajin(S4S4); Zaomeisu(S3Sd); Qiyuesu (S4Sd); Beifeng(S4S26m); Jinfeng(S19S34).The pear ’Zaosu’ is the progeny of ’Pingguoli’×’Shenbuzhi’. Artificial self-pollination had been done on ’Zaosu’. The pollen tubes growths in the styles were observed at96h after self-pollination, and the fruit sets were calculated30days later. The results showed that ’Zaosu’ is self-incompatible, which means that the pollen tubes could not grow at the bottom of style at96h after self-pollination.