Proteomic Analysis Reveals Protein Expression Difference For The Pollen Germination Of "YaLi"(Pyrus Bretschneideri Rehd.)and "Jinzhui" In Vitro By ITRAQ

Pear,displaying a typical S-RNase-based gametophytic self-incompatibility(GSI),is one of the most important fruit tree in Asia and our country."JinZhui" is a spontaneous self-compatible mutant of "YaLi"(Pyrus bretschneideri Rehd).In this study,we identified differentially expressed proteins between the pollen from"JinZhui" and "YaLi" which cultivated in vitro by using the Isobaric Tag for Relative and Absolute Quantification(iTRAQ)labeling technique.The main results were as follows:1.Cultivated the pollen of "JinZhui" and "YaLi" in liquid culture medium for 1 h,then added the S-RNase to the culture medium.The results showed that S-RNase from "JinZhui" and "YaLi" inhibited the pollen growth of "YaLi",but have no obvious influence on the pollen growth of "JinZhui".The pollen without add in any S-RNase used as control and we found that the pollen of control grew well.2.We sequenced protein samples from the pollen of "JinZhui" and "YaLi"which cultivated in vitro by using iTRAQ labeling technique.We identified 306 812 spectra by two-dimensional liquid chromatography tandem mass spectrometry,in which 39 301 matched known spectra,38 842 spectra matched unique spectra,20909 matched peptides,15788 matched unique peptides,and 3878 matched proteins,respectively.A total of 173 differentially expressed proteins were fund and among these DEPs,93 showed an increase and 80 showed a decrease in abundance.3.The ubiquitin/26S proteasome pathway is a main route for degradation of non-self S-RNase.We fund that some DEPs related to the metabolism of ubiquitin such as UBP14?UBP12?UPL1 showed a decrease in abundance in "JinZhui".Therefore,we concluded that in "JinZhui" the ubiquitin pathway was inhibited and led to self-compatibility.Some DEPs related to the function of membrane transport such as PME7.PME13?LTP3 and MALD3 were up-regulated proteins in "JinZhui",so we suggested that the membrane transport in "JinZhui" is stronger than in"YaLi".In addition,we fund some DEPs related to the growth of pollen and pollen tube.and a important F-box protein,F-box kelch-repeat protein At3g06240,which maybe directly involved in the self-incompatibily.