SIP 1 participates in regulation of flowering time in rice by recruiting OsTrx1 to Ehd1

• Published in: The New phytologist Vol. 219; no. 1; pp. 422 - 435
• Main Authors: Jiang, Pengfei, Wang, Shiliang, Zheng, Han, Li, Hao, Zhang, Fei, Su, Yanhua, Xu, Zuntao, Lin, Haiyan, Qian, Qian, Ding, Yong
• Format: Journal Article
• Language: English
• Published: 01.07.2018
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/nph.15122

Summary Flowering time (heading date) in rice ( Oryza sativa ) is an important agronomic trait that determines yield. The levels of histone H3 lysine 4 trimethylation (H3K4me3) modulated by TRITHORAX ‐like proteins regulate gene transcription, flowering time and environmental stress responses. However, plant TRITHORAX ‐like proteins have no known DNA ‐binding domain, and therefore the mechanism that gives sequence specificity to these proteins remains unclear. Here, we show that the rice TRITHORAX ‐like protein OsTrx1 is recruited to its target, Early heading date 1 ( Ehd1 ), by the C2H2 zinc finger protein SDG 723/OsTrx1/Os SET 33 Interaction Protein 1 ( SIP 1). SIP 1 binds to the promoter of Ehd1 and interacts with OsTrx1. Mutations in SIP 1 led to a late heading date under long‐day and short‐day conditions. Defects in OsTrx1 or SIP 1 led to reduced H3K4me3 levels at Ehd1 , thus reducing Ehd1 expression. Together, our results show that the transcription factor SIP 1 interacts with OxTrx1, allowing OsTrx1 to specifically target Ehd1 , altering H3K4me3 levels, increasing Ehd1 expression and thereby promoting flowering.