AUTHOR=Deng Luchang , Zhang Siwei , Wang Geling , Fan Shijun , Li Meng , Chen Weilan , Tu Bin , Tan Jun , Wang Yuping , Ma Bingtian , Li Shigui , Qin Peng 

TITLE=Down-Regulation of OsEMF2b Caused Semi-sterility Due to Anther and Pollen Development Defects in Rice

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.01998

DOI=10.3389/fpls.2017.01998

ISSN=1664-462X

ABSTRACT=<p>Anther and pollen development are crucial processes of plant male reproduction. Although a number of genes involved in these processes have been identified, the regulatory networks of pollen and anther development are still unclear. <italic>EMBRYONIC FLOWER 2b</italic> (<italic>OsEMF2b</italic>) is important for rice development. Its biological function in floral organ, flowering time and meristem determinacy have been well-studied, but its role, if only, on male reproduction is still unknown, because null mutants of <italic>OsEMF2b</italic> barely have anthers. In this study, we identified a weak allele of <italic>OsEMF2b</italic>, <italic>osemf2b-4</italic>. The T-DNA insertion was located in the promoter region of <italic>OsEMF2b</italic>, and <italic>OsEMF2b</italic> expression was significantly decreased in <italic>osemf2b-4</italic>. The <italic>osemf2b-4</italic> mutant exhibited much more normal anthers than null mutants of <italic>OsEMF2b</italic>, and also showed defective floret development similar to null mutants. Cytological analysis showed various defects of anther wall and pollen development in <italic>osemf2b-4</italic>, such as slightly or extremely enlarged tapetum, irregular or normal morphology microspores, and partial or complete sterility. <italic>OsEMF2b</italic> was highly expressed in tapetum and microspores, and the protein was localized in the nucleus. The expression of 15 genes essential for anther and pollen development was investigated in both WT and <italic>osemf2b-4</italic>. Fourteen genes including <italic>GAMYB</italic> was up-regulated, and only <italic>PTC1</italic> was down-regulated in <italic>osemf2b-4</italic>. This suggests that up-regulated <italic>GAMYB</italic> and down-regulated <italic>PTC1</italic> might contribute to the defective anther and pollen development in <italic>osemf2b-4</italic>. Overall, our work suggests that <italic>OsEMF2b</italic> plays an essential role during post-meiotic anther and pollen development.</p>