The H3K27me3 demethylase REF6 promotes leaf senescence through directly activating major senescence regulatory and functional genes in Arabidopsis

• Published in: PLoS genetics Vol. 15; no. 4; p. e1008068
• Main Authors: Wang, Xiaolei, Gao, Jiong, Gao, Shan, Song, Yi, Yang, Zhen, Kuai, Benke
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 10.04.2019; Public Library of Science (PLoS)
• Subjects: Aging (Biology); Arabidopsis; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Binding Sites - genetics; Biodegradation; Biodiversity; Biology and Life Sciences; Botanical research; Chlorophyll; Chlorophyll - metabolism; Chloroplast Proteins - genetics; Chloroplast Proteins - metabolism; Demethylation; Disease resistance; DNA binding proteins; DNA methylation; Engineering and Technology; Epigenesis, Genetic; Epigenetic inheritance; Flowering; Gene expression; Gene Expression Regulation, Developmental; Gene Expression Regulation, Plant; Genes, Plant; Genes, Regulator; Genetic aspects; Genetic engineering; Genetic regulation; Genomes; Germination; Histone H3; Histones; Jumonji Domain-Containing Histone Demethylases - genetics; Jumonji Domain-Containing Histone Demethylases - metabolism; Laboratories; Leaves; Life sciences; Lipoxygenase; Lysine; Medicine and Health Sciences; Methylation; Models, Genetic; Mutation; Net losses; Orthophosphate; Physical Sciences; Physiological aspects; Phytoalexins; Plant diseases; Plant Leaves - genetics; Plant Leaves - growth & development; Plant Leaves - metabolism; Plants, Genetically Modified; Promoter Regions, Genetic; Protein binding; Pyruvic acid; Seed germination; Seeds; Senescence; Transcription (Genetics); Transcription activation; Transcription factors; Transcription Factors - genetics; Transcription Factors - metabolism; Zinc finger proteins; China
• ISSN: 1553-7404; 1553-7390; 1553-7404
• DOI: 10.1371/journal.pgen.1008068

The roles of histone demethylation in the regulation of plant flowering, disease resistance, rhythmical response, and seed germination have been elucidated recently; however, how histone demethylation affects leaf senescence remains largely unclear. In this study, we exploited yeast one-hybrid (Y1H) to screen for the upstream regulators of NONYELLOWING1 (NYE1), and identified RELATIVE OF EARLY FLOWERING6 (REF6), a histone H3 lysine 27 tri-methylation (H3K27me3) demethylase, as a putative binding protein of NYE1 promoter. By in vivo and in vitro analyses, we demonstrated that REF6 directly binds to the motif CTCGYTY in NYE1/2 promoters through its zinc finger domain and positively regulates their expression. Loss-of-function of REF6 delayed chlorophyll (Chl) degradation, whereas overexpression of REF6 accelerated Chl degradation. Subsequently, we revealed that REF6 positively regulates the general senescence process by directly up-regulating ETHYLENE INSENSITIVE 2 (EIN2), ORESARA1 (ORE1), NAC-LIKE, ACTIVATED BY AP3/PI (NAP), PYRUVATE ORTHOPHOSPHATE DIKINASE (PPDK), PHYTOALEXIN DEFICIENT 4 (PAD4), LIPOXYGENASE 1 (LOX1), NAC DOMAIN CONTAINING PROTEIN 3 (AtNAC3), and NAC TRANSCRIPTION FACTOR-LIKE 9 (NTL9), the key regulatory and functional genes predominantly involved in the regulation of developmental leaf senescence. Importantly, loss-of-function of REF6 increased H3K27me3 levels at all the target Senescence associated genes (SAGs). We therefore conclusively demonstrate that H3K27me3 methylation represents an epigenetic mechanism prohibiting the premature transcriptional activation of key developmentally up-regulated senescence regulatory as well as functional genes in Arabidopsis.