Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Science, South China Normal University, Guangzhou, 510631, China.
State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing, 100871, China.
Plant Sci. 2018 Jun;271:127-132. doi: 10.1016/j.plantsci.2018.03.021. Epub 2018 Mar 22.
The SWI/SNF complex is crucial to chromatin remodeling in various biological processes in different species, but the distinct functions of its components in plant development remain unclear. Here we uncovered the role of SWI3B, a subunit of the Arabidopsis thaliana SWI/SNF complex, via RNA interference. Knockdown of SWI3B resulted in an upward-curling leaf phenotype. Further investigation showed that the RNA level of IAA carboxyl methyltransferase 1 (IAMT1), encoding an enzyme involved in auxin metabolism, was dramatically elevated in the knockdown (SWI3B-RNAi) plants. In addition, activation of IAMT1 produced a leaf-curling phenotype similar to that of the SWI3B-RNAi lines. Database analysis suggested that the last intron of IAMT contains a site of polymerase V (Pol V) stabilized nucleosome, which may be associated with SWI3B. Data from a micrococcal nuclease (MNase) digestion assay showed that nucleosome occupancy around this site was downregulated in the leaves of SWI3B-RNAi plants. In addition, knockdown of IAMT1 in the SWI3B-RNAi background repressed the abnormal leaf development. Thus, SWI3B-mediated chromatin remodeling is critical in regulating the expression of IAMT1 in leaf development.
SWI/SNF 复合物对于不同物种的各种生物学过程中的染色质重塑至关重要，但该复合物的成分在植物发育中的独特功能仍不清楚。在这里，我们通过 RNA 干扰揭示了拟南芥 SWI/SNF 复合物的一个亚基 SWI3B 的作用。SWI3B 的敲低导致叶片向上卷曲的表型。进一步的研究表明，参与生长素代谢的酶 IAA 羧基甲基转移酶 1（IAMT1）的 RNA 水平在敲低（SWI3B-RNAi）植物中显著升高。此外，IAMT1 的激活产生了类似于 SWI3B-RNAi 系的叶片卷曲表型。数据库分析表明，IAMT 的最后一个内含子包含一个聚合酶 V（Pol V）稳定核小体的位点，该位点可能与 SWI3B 相关。微球菌核酸酶（MNase）消化测定的数据表明，SWI3B-RNAi 植物叶片中该位点周围核小体的占有率下调。此外，在 SWI3B-RNAi 背景下敲低 IAMT1 抑制了异常叶片发育。因此，SWI3B 介导的染色质重塑对于调节 IAMT1 在叶片发育中的表达至关重要。
