title: Small RNAs in pollen.
abstract: In plants, each pollen mother cell undergoes two rounds of cell divisions to form a mature pollen grain, which contains a vegetative cell (VC) and two sperm cells (SC). As a companion cell, the VC carries the SCs to an ovule by germinating a pollen tube. In-depth sequencing analyses of mature pollen showed that microRNAs (miRNAs) and short interfering RNAs (siRNAs) are present in both the VC and SCs. Additionally, epigenetically-regulated transposable elements (TEs) are reactivated in the VC and these TE mRNAs are further processed into 21-nt epigenetically reactivated siRNA (easiRNA) in SCs, which prevent 24-nt siRNA accumulation and sequester miRNA loading. Small RNAs are thought to move from the VC to SCs, where they regulate gene expression and reinforce TE silencing. Here, we summarize current knowledge of the biogenesis and function of miRNAs, siRNAs, and easiRNAs in pollen, emphasizing how these different small RNAs coordinately contribute to sperm cell formation and TE silencing.
authors: State Key Laboratory of Genetic Engineering, Collaborative Innovation Center for Genetics and Development, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai, 200438, China.
authors: Hui
authors: H
authors: He
authors: TianYu
authors: T
authors: Yang
authors: WenYe
authors: W
authors: Wu
authors: BingLian
authors: B
authors: Zheng
mesh_terms: D044127:Epigenesis, Genetic; D035683:MicroRNAs / Q000235:genetics; D011058:Pollen / Q000235:genetics*; D018749:RNA, Plant / Q000235:genetics*; D034741:RNA, Small Interfering / Q000235:genetics
chemical_list: D035683:MicroRNAs; D018749:RNA, Plant; D034741:RNA, Small Interfering