阿拉伯芥組蛋白去甲基化酶JMJ28藉由促進CONSTANS表達參與開花調控

Abstract

組蛋白去甲基化酶藉由表觀遺傳修飾影響植物生長發育。組蛋白去甲基酶JMJ28屬於KDM3/JHDM2類並具有組蛋白H3賴胺酸9 (H3K9) 去甲基酶的功能。在本研究中發現，jmj28-1及jmj28-2突變體在長日照及短日照的條件下都有延遲開花的表現型。相較於野生型，參與光週期調控開花的基因CO及FT的基因表現在jmj28突變體中有顯著性下調。過量表達JMJ28的轉殖株則表現出提早開花的表現型，並且CO及FT的基因表現有顯著上升。另外，CO上的H3K9甲基化程度在jmj28突變體中有顯著性上升，而在JMJ28的過表達轉殖株則有顯著下降。此外JMJ28會與轉錄因子FBH及TCP有交互作用。JMJ28會直接結合在CO啟動子上，而JMJ28的這種結合作用至少部分依賴於FBH。這些結果說明JMJ28可能透過調控H3K9去甲基化的方式來影響CO基因表現，並參與阿拉伯芥開花調控。

Histone demethylases (HDMs) play important roles in plant growth and development by modulating epigenetic processes. The histone demethylase JMJ28 belongs to the KDM3/JDHM2 group and has H3K9 demethylation activity. In this study, it was found that the JMJ28 knockout mutants, jmj28-1 and jmj28-2, displayed late flowering phenotypes under both long day and short day conditions. The expression of CO and FT was down regulated in jmj28 mutants. Overexpression of JMJ28 resulted in an early flowering phenotype and increased expression of CO and FT. In addition, the H3K9me2 level of CO near the transcription start site was increased in the jmj28 mutants but decreased in the JMJ28 overexpressing transgenic plants. Furthermore, JMJ28 can interact with the transcription factors, FBHs and TCPs. Moreover, JMJ28 can target on the CO promoter, and the binding of JMJ28 to CO is at least partially dependent on FBHs. Together, these results suggest that JMJ28 is involved in the flowering time by regulating the expression of CO through H3K9 demethylation.