Yan Yan, Li Chao, Liu Zhen, Zhuang Jun-Jie, Kong Jia-Rui, Yang Zhen-Kun, Yu Jie, Shah Alam Mohammad, Ruan Cheng-Cheng, Zhang Heng-Mu, Xu Jian-Hong
Institute of Crop Science, Zhejiang Key Laboratory of Crop Germplasm, Zhejiang University, Hangzhou 310058, China.
Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
J Exp Bot. 2022 Dec 8;73(22):7273-7284. doi: 10.1093/jxb/erac367.
High temperature (HT) can affect the accumulation of seed storage materials and cause adverse effects on the yield and quality of rice. DNA methylation plays an important role in plant growth and development. Here, we identified a new demethylase gene OsDML4 and discovered its function in cytosine demethylation to affect endosperm formation. Loss of function of OsDML4 induced chalky endosperm only under HT and dramatically reduced the transcription and accumulation of glutelins and 16 kDa prolamin. The expression of two transcription factor genes RISBZ1 and RPBF was significantly decreased in the osdml4 mutants, which caused adverse effects on the formation of protein bodies (PBs) with greatly decreased PB-II number, and incomplete and abnormally shaped PB-IIs. Whole-genome bisulfite sequencing analysis of seeds at 15 d after pollination revealed much higher global methylation levels of CG, CHG, and CHH contexts in the osdml4 mutants compared with the wild type. Moreover, the RISBZ1 promoter was hypermethylated but the RPBF promoter was almost unchanged under HT. No significant difference was detected between the wild type and osdml4 mutants under normal temperature. Our study demonstrated a novel OsDML4-mediated DNA methylation involved in the formation of chalky endosperm only under HT and provided a new perspective in regulating endosperm development and the accumulation of seed storage proteins in rice.
高温（HT）会影响种子贮藏物质的积累，并对水稻的产量和品质产生不利影响。DNA甲基化在植物生长发育中起重要作用。在此，我们鉴定了一个新的去甲基化酶基因OsDML4，并发现其在胞嘧啶去甲基化中影响胚乳形成的功能。OsDML4功能缺失仅在高温下诱导垩白胚乳形成，并显著降低谷蛋白和16 kDa醇溶蛋白的转录和积累。在osdml4突变体中，两个转录因子基因RISBZ1和RPBF的表达显著降低，这对蛋白体（PBs）的形成产生不利影响，导致PB-II数量大幅减少，PB-II不完整且形状异常。授粉后15天种子的全基因组亚硫酸氢盐测序分析显示，与野生型相比，osdml4突变体中CG、CHG和CHH背景的整体甲基化水平要高得多。此外，在高温下，RISBZ1启动子发生高甲基化，但RPBF启动子几乎没有变化。在正常温度下，野生型和osdml4突变体之间未检测到显著差异。我们的研究证明了一种新的由OsDML4介导的DNA甲基化，其仅在高温下参与垩白胚乳的形成，并为调控水稻胚乳发育和种子贮藏蛋白积累提供了新的视角。
