Differences in protein abundance between germinated and nongerminating Asian pear pollen

To produce pollen with a uniform germination rate, thereby increasing the efficiency of artificial pollination, it is necessary to identifying factors involved in pollen germination. Although several proteins associated with pollen germination have been identified and functionally characterized, the pollen germination process is still not well understood. Thus, this study identifies the factors involved in pollen germination and pollen tube growth by separating germinated and nongerminating pollen every hour for 4 h during in vitro pollen germination and comparing protein abundances in each group to those in mature, pre-germination pollen at each time point through proteomics analysis. As a result, 185 differentially expressed proteins were identified, and protein abundances varied depending on germination status, with some proteins being up- and down-regulated only in germinated or nongerminating pollen. Functional annotations were added to the identified proteins, and most were related to carbohydrate metabolism and energy, defense/stress response, and protein synthesis and processing. Our study is the first attempt to analyze the proteins in pollen separated depending on whether they germinated under germination conditions, and our findings may contribute to the production of pollen with a stable germination rate.