Among the Rosaceae species, the gametophytic self-incompatibility (GSI) is controlled by a single multi-allelic S locus, which is composed of the pistil-S and pollen-S genes. The pistil-S gene encodes a polymorphic ribonuclease (S-RNase), which is essential for identifying self-pollen. However, the S-RNase system has not been fully characterized. In this study, the self-S-RNase inhibited the Ca~(2+)-permeable channel activity at pollen tube apices and the selectively decreased phospholipase C ( PLC ) activity in the plasma membrane of Pyrus pyrifolia pollen tubes. Self-S-RNase decreased the Ca~(2+)influx through a PLC -mediated signaling pathway. Phosphatidylinositol-specific PLC has a 26-amino acid insertion in pollen tubes of the ‘Jinzhuili’ cultivar, which is a spontaneous self-compatible mutant of the ‘Yali’ cultivar. ‘Yali’ plants exhibit a typical S-RNase-based GSI. Upon self-pollination, PLC gene expression is significantly higher in ‘Jinzhuili’ pollen tubes than that in ‘Yali’ pollen tubes. Moreover, the PLC in pollen tubes can only interact with one of the two types of S-RNase from the style. In the Pyrus x bretschneideri Rehd, the PLC directly interacted with the S_(7)-RNase in the pollen tube, but not with the S_(34)-RNase. Collectively, our results reveal that the effects of S-RNase on PLC activity are required for S-specific pollen rejection, and that PLC -IP_(3)participates in the self-incompatibility reaction of Pyrus species.
展开▼
机译：在蔷薇科物种中，配子体自交不亲和性（GSI）受单个多等位基因S基因座控制，该基因座由雌蕊-S和花粉-S基因组成。雌蕊S基因编码一个多态性核糖核酸酶（S-RNase），这对于鉴定自花粉是必不可少的。但是，S-RNase系统尚未完全表征。在这项研究中，自我S-RNase抑制了Pyrus pyrifolia花粉管质膜中Ca〜（2+）的通道活性，并选择性降低了磷脂酶C（PLC）的活性。 Self-S-RNase通过PLC介导的信号通路减少Ca〜（2+）流入。磷脂酰肌醇特定的PLC在“金zhu里”品种的花粉管中插入了26个氨基酸，该花粉管是“雅利”品种的自发自交突变体。 “ Yali”植物表现出典型的基于S-RNase的GSI。自花授粉后，“金zhu里”花粉管中的PLC基因表达明显高于“亚里”花粉管中的PLC基因表达。此外，花粉管中的PLC只能与两种S-RNase类型中的一种相互作用。在Pyrus x bretschneideri Rehd中，PLC直接与花粉管中的S_（7）-RNase相互作用，但不与S_（34）-RNase相互作用。总的来说，我们的结果表明，S-RNase对PLC活性的影响是S特异性花粉排斥所必需的，并且PLC -IP_（3）参与了梨属植物的自交不亲和反应。
展开▼
