Exogenous abscisic acid represses rice flowering via SAPK8-ABF1-Ehd1/Ehd2 pathway

Title : Exogenous abscisic acid represses rice flowering via SAPK8-ABF1-Ehd1/Ehd2 pathway

Abstract:

Rice flowering is a primary agronomic trait that determines yield and ecological adaptability in particular regions. ABA is essential in rice flowering, but the underlying molecular mechanism is poorly understood. Here, we report the identification of a "SAPK8-ABF1-Ehd1/Ehd2" pathway, through which exogenous ABA represses rice flowering in a photoperiod-independent manner. Under short- and long-day conditions, simultaneous knock-out of ABF1 and its homolog bZIP40 accelerated flowering. At the same time, SAPK8 and ABF1 over-expression lines exhibited delayed flowering and hypersensitivity to ABA-mediated flowering repression. After perceiving the ABA signal, SAPK8 physically binds to and phosphorylates ABF1 to enhance its binding on the promoters of master positive flowering regulators Ehd1 and Ehd2. By interacting with FIE2, ABF1 recruited the PRC2 complex to deposit H3K27me3 suppressive histone modification on Ehd1 and Ehd2 to suppress these genes' transcription, eventually leading to later flowering. The current study shed a novel insight into the ABA inhibitive effects on rice flowering.

Audience Take Away Notes:

• We report the identification of a  ‘SAPK8-ABF1-Ehd1/Ehd2’ pathway in rice flowering
• Using yeast two-hybrid,Pull down, BiFC and kinase assays, SAPK8 interacted and phosphorylated ABF1. ABF1 directly bound to the promoters of Ehd1 and Ehd2 using ChIP-qPCR, EMSA, and LUC transient transcriptional activity assay, and suppressed the transcription of these genes. Upon interacting with FIE2, ABF1 recruited PRC2 complex to deposit H3K27me3 suppressive histone modification on Ehd1 and Ehd2 to suppress these genes transcription, thereby leading to later flowering
• Our work highlighted the biological functions of SAPK8 and ABF1 in ABA signaling, flowering control and the involvement of a PRC2-mediated epigenetic repression mechanism in the transcription regulation governed by ABF1 on ABA-mediated rice flowering repression

Biography:

Dr. Wang Yifeng is an associate researcher and master tutor at China Rice Research Institute. He graduated from Shangdong University, China, with a bachelor's degree in biotechnology in 2009; In 2014, he graduated from Zhejiang University, China, majoring in botany; He worked at the China Rice Research Institute in 2015. He is mainly engaged in cloning and functional research of genes related to seed dormancy and germination. He presided over projects such as the National Natural Science Foundation of China, the Natural Science Foundation of Zhejiang Province, and the Key R&D project of Zhejiang Province. As the first/co-first/corresponding author, he has published 14 articles in New Phytologist, Journal of Experimental Botany, Plant Physiology and Biochemistry, and other magazines, with a cumulative impact factor of>40. As the principal author, he has published 15 papers in Molecular Plant, Plant Cell, Plant Biotechnology Journal, Plant Physiology, and other magazines and has obtained 6 invention patents.
Research fields: cloning, functional research, and breeding utilization of genes related to rice dormancy and germination.