Research Progress on Calcium Ion in Gametophytic Self-Incompatibility

Calcium ions are involved in plant self-incompatibility response as important signaling substances in cells. In the sporophytic self-incompatibility response, Ca²⁺ enters the stigma papilla cells and plays a key role in inhibiting incompatible pollen tube growth. In the gametophytic self-incompatibility reaction of Papaveraceae, the female determinants in the style (PrsS) and the male determinants in the pollen (PrpS) recognize each other, promote extracellular Ca²⁺ influx into the incompatible pollen tube, destroy the calcium ion gradient at the tip of the pollen tube, and inhibit the pollen tube growth. In the S-RNase-based Rosaceae game-tophytic self-incompatibility response, it is still unclear how the S-RNase interacts with the male determinant and how the S-RNase specifically degrades the RNA in the pollen tube. Therefore, we reviewed the research progress on the role of Ca²⁺ in self-incompatibility and, based on our research results, proposed a role model of Ca²⁺ as a signal substance in the gametophyte self-incompatibility response in Rosaceae.