EN
The objective of this study was to examine whether S-RNase plays a specific role in the pre-germinated Pyrus pollen. Effects of exogenous RNase and endogenous S-RNase on concentration of cytosolic-free calcium ([Ca⁺²]i) variation of pre-germinated Pyrus pollen were studied. [Ca⁺²]i variation caused by different Rnases were complex. In 1 h after being cultured, exogenous RNase, RNase T1 and RNase A, and endogenous incompatible ‘Hohsui’ RNase promoted the [Ca⁺²]i of ‘Hohsui’ pollen. Acid proteins of ‘Hohsui’ had no remarkable influence on the [Ca⁺²]i of self-pollen. Endogenous compatible ‘Kohsui’ RNase reduced the [Ca⁺²]i of ‘Hohsui’ pollen, but compatible ‘Hohsui’ RNase can stimulate the [Ca⁺²]i of ‘Kohsui’ pollen. RNase T1, RNase A and incompatible ‘Kohsui’ S-RNase can also make ‘Kohsui’ pollen [Ca⁺²]i increase. Different from ‘Hohsui’ pollen, acid proteins of ‘Hohsui’ pull down the ‘Kohsui’ pollen [Ca⁺²]i remarkably. Conclusion can be made that during the prophase of pollen germination, endogenous S-RNase has no specific effect on pollen [Ca⁺²]i changes.