Non-separated microspores 1 controls male meiotic callose deposition at the cell plate in rice  

作　　者：Haiyuan Chen Suobing Zhang Weijie Tang Jun Tang Jing Lin Xianwen Fang Yunhui Zhang 

机构地区：[1]Provincial Key Laboratory of Agrobiology,Institute of Germplasm Resources and Biotechnology,Jiangsu Academy of Agricultural Sciences,Nanjing 210014,Jiangsu,China [2]Zhongshan Biological Breeding Laboratory,Nanjing 210014,Jiangsu,China [3]Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops,Yangzhou University,Yangzhou 225009,Jiangsu,China

出　　处：《The Crop Journal》2024年第6期1559-1568,共10页作物学报（英文版）

基　　金：supported by grants from the National Natural Science Foundation of China (31971871);Open Competition Mechanism to Select the Best Candidates Fund of Jiangsu Province (JBGS[2021]012);Zhongshan Biological Breeding Laboratory (BM2022008-01,BM2022008-03).

摘　　要：In flowering plants, callose(β-1,3-glucan) plays a vital role in pollen development, especially in the separation and development of microspores. However, the molecular mechanism of callose deposition during rice pollen development remains unclear. In this study, we isolated and characterized a novel rice pollen defective mutant, non-separated microspores 1(nsm1), which produced “dyad” or “tetrad” pollen grains. Cytological analysis indicated disrupted interstitial callose deposition at the cell plate of dyads and tetrads in nsm1 pollens. This disruption caused sporopollenin to be massively deposited outside of the junction where the interstitial callose wall connected with the peripheral callose wall, or unevenly distributed on the interstitial pollen primexine at the late meiosis stage. Consequently, an excess tectum-like layer was formed outside of the junction, connecting with the tectum of two microspores during later developmental stages, which prevented the separation of microspores. Additionally, in the linkage area, the tectum of two microspores gradually fused or degenerated, resulting in a decreased contact area between microspores and the anther locule. Therefore, the defect in callose deposition resulted in unsuccessful separation of microspores, abnormal deposition of pollen exine, and also affected the accumulation of materials in microspores, resulting in pollen semi-sterility. NSM1, encoding a callose synthase located in the Golgi body, is ubiquitously expressed in anthers with its peak expression at the young microspore stage. The in vitro enzyme activity assay confirmed that NSM1 possesses callose synthase activity, and the enzyme activity in the nsm1 mutants was significantly reduced.Phylogenetic analysis indicated that NSM1 and its orthologs play a highly conserved role in callose biosynthesis among plant species. Taken together, we propose that NSM1 plays an essential role in male meiotic callose synthesis and later pollen wall development.

关 键 词：Callose synthase Microspore separation EXINE SPOROPOLLENIN RICE 

分 类 号：S511[农业科学—作物学]