Ubiquitin-dependent Argonauteprotein MEL1 degradation is essential for rice sporogenesis and phasiRNA target regulation. Issue 8 (18th May 2021)

• Record Type: Journal Article
• Authors: Lian, Jian-Ping; Yang, Yu-Wei; He, Rui-Rui; Yang, Lu; Zhou, Yan-Fei; Lei, Meng-Qi; Zhang, Zhi; Huang, Jia-Hui; Cheng, Yu; Liu, Yu-Wei; Zhang, Yu-Chan; Chen, Yue-Qin
• Is Part Of: The Plant Cell. Volume 33:Issue 8(2021)
• Page Start: 2685
• Page End: 2700
• Publication Date: 2021-05-18
• DOI: 10.1093/plcell/koab138
• Languages: English
• ISSNs: 1040-4651

Abstract

Abstract: MEIOSIS ARRESTED AT LEPTOTENE1 (MEL1), a rice ( Oryza sativa ) Argonaute (AGO) protein, has been reported to function specifically at premeiotic and meiotic stages of germ cell development and is associated with a novel class of germ cell-specific small noncoding RNAs called phased small RNAs (phasiRNAs). MEL1 accumulation is temporally and spatially regulated and is eliminated after meiosis. However, the metabolism and turnover (i.e. the homeostasis) of MEL1 during germ cell development remains unknown. Here, we show that MEL1 is ubiquitinated and subsequently degraded via the proteasome pathway in vivo during late sporogenesis. Abnormal accumulation of MEL1 after meiosis leads to a semi-sterile phenotype. We identified a monocot-specific E3 ligase, XBOS36, a CULLIN RING-box protein, that is responsible for the degradation of MEL1. Ubiquitination at four K residues at the N terminus of MEL1 by XBOS36 induces its degradation. Importantly, inhibition of MEL1 degradation either by XBOS36 knockdown or by MEL1 overexpression prevents the formation of pollen at the microspore stage. Further mechanistic analysis showed that disrupting MEL1 homeostasis in germ cells leads to off-target cleavage of phasiRNA target genes. Our findings thus provide insight into the communication between a monocot-specific E3 ligase and an AGO protein during plant reproductive development. Abstract : The degradation of Argonaute protein MEL1 is mediated by a monocot-specific E3 ubiquitin ligase XBOS36 to avoid off-target regulation of phasiRNAs during rice sporogenesis.