Effects of interaction between pollen coat eluates and pistil at the molecular level in self-compatible and self-incompatible plants of Lolium multiflorum Lam.

Two-dimensional electrophoresis (2-DE) of soluble proteins and enzymes was performed and specific activities of 5 enzymes (esterase, pectinesterase, acid phosphatase, protease and diaphorase) were determined in stigmas of Lolium multiflorum (Italian ryegrass) treated with self or foreign pollen coat eluates (pc). Also, a low-molecular-weight fraction of the treated self-compatible (SC) and self-incompatible (SI) stigmas was analyzed by high-pressure liquid chromatography (HPLC). The treatment of stigmas with foreign pollen induced the loss of 42% of the control sample proteins in SC plants but only of 5.5% in SI plants. In contrast, the treatment of stigmas with foreign pollen induced the loss of 15% proteins in SC plants and of 29% in SI plants. Specific activities of esterase, pectinesterase and diaphorase were higher in SC than in SI stigmas. The 2-DE enzyme patterns indicated qualitative relationships between the presence of some isoforms of acid phosphatase or protease and the treatment with self or foreign pc in SC and SI stigmas. No changes were observed in HPLC profiles of the low-molecular-weight fraction from SC and SI stigmas treated or not with pc. The presented results revealed different reactions of SC and SI stigmas to the treatment with self or foreign pc. Further investigations may explain if any of the observed reactions represent specific reorientations in the style, facilitating cross- or self-pollination.