Li M F, Li X F, Han Zh H, Shu H R, Li T Zh
Laboratory of Fruit Cell and Molecular Breeding, China Agricultural University, Beijing, China.
Plant Biol (Stuttg). 2009 Sep;11(5):774-83. doi: 10.1111/j.1438-8677.2008.00180.x.
Yan Zhuang and Jin Zhui are spontaneous bud mutants of Chinese pear (Pyrus bretschneideri Rehd.) from Ya Li. Both fruit set rate and seed number after self-pollination, together with pollen tube growth, prove that Yan Zhuang and Jin Zhui are self-compatible. The fruit set rate and seed number after cross-pollination suggest that the self-compatibility of Yan Zhuang and Jin Zhui may be due to natural mutations of the stylar S allele and pollen S allele, respectively. PCR amplification of the S-RNase gene in self-pollinated progeny of Yan Zhuang and Jin Zhui show that they contain point mutations in the stylar S(21) allele and pollen S(34) allele, respectively. The cDNA sequence of the Yan Zhuang stylar S-RNase gene revealed that the 182nd nucleotide of the S(21)-RNase (cDNA) sequence had been substituted resulting in a Gly to Val mutation, and this might affect the stability of the S-RNase. In addition, Western blotting showed that one Yan Zhuang stylar S-RNase was absent and the expression level of another S-RNase protein was decreased compared to Ya Li. Therefore, we suggest that the self-compatibility of Yan Zhuang is caused by a point mutation in an S(21)-RNase nucleotide.
鸭梨的鸭庄和金坠是中国梨（Pyrus bretschneideri Rehd.）的自发芽变品种。自花授粉后的坐果率和种子数，以及花粉管生长情况，都证明鸭庄和金坠是自交亲和的。异花授粉后的坐果率和种子数表明，鸭庄和金坠的自交亲和性可能分别是由于花柱S等位基因和花粉S等位基因的自然突变所致。对鸭庄和金坠自花授粉后代的S-RNase基因进行PCR扩增表明，它们分别在花柱S(21)等位基因和花粉S(34)等位基因中存在点突变。鸭庄花柱S-RNase基因的cDNA序列显示，S(21)-RNase（cDNA）序列的第182个核苷酸发生了替换，导致甘氨酸突变为缬氨酸，这可能会影响S-RNase的稳定性。此外，蛋白质免疫印迹分析表明，与鸭梨相比，鸭庄的一种花柱S-RNase缺失，另一种S-RNase蛋白的表达水平降低。因此，我们认为鸭庄的自交亲和性是由S(21)-RNase核苷酸中的一个点突变引起的。
