Title : Morphological aspect and molecular mechanism of pollen hydration on pollination in Arabidopsis thaliana
Abstract:
In flowering plants, sexual reproduction is a complex and orchestrated series of events regulated by multiple processes for successful seed production, including capturing and adhesion of pollen grains onto a surface of stigmatic papilla, foot formation to strengthen pollen–stigma interaction, hydration and germination of pollen grains, pollen tube elongation into the stigma and style, pollen tube guidance towards the ovule, and fertilization of egg cells and central nuclei, termed double fertilization. Among them, pollination is the first important step in plant reproduction to bring together the male and female gametophytes. In Arabidopsis thaliana, it occurs at a surface of the stigmatic papilla cell. After pollen recognition, accepted pollen grains rapidly start hydration and germination, and pollen tube exactly penetrates into the stigmatic surface, elongates through stigma and style, and finally fertilizes with a female gametophyte in the ovule. While it has been studied for many years, the knowledge base about molecular mechanisms underlying these sequential pollination events are still largely unclear. In this study, we focus on the pollen hydration process, as a mid-pollination appearance for successful reproduction. Coupled with the time-series imaging analysis of pollination and the gene expression information obtained via lasermicrodissection-RNA sequencing analysis of Arabidopsis papilla cell, we found that pollen hydration starts within 5 min and completed in approximately 45 min after pollination and the membrane bound-water channel proteins, belonging to the Major Intrinsic Protein family, would be key players of water transport from the pistil to pollen grains for successful pollen hydration.
