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Trithorax‐group proteins ARABIDOPSIS TRITHORAX4 (ATX4) and ATX 5 function in abscisic acid and dehydration stress responses
Author(s) -
Liu Yutong,
Zhang Ai,
Yin Hao,
Meng Qingxiang,
Yu Xiaoming,
Huang Shuangzhan,
Wang Jie,
Ahmad Rafiq,
Liu Bao,
Xu ZhengYi
Publication year - 2018
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.14933
Subject(s) - abscisic acid , arabidopsis , biology , chromatin , mutant , abiotic stress , arabidopsis thaliana , transcription factor , microbiology and biotechnology , rna polymerase ii , gene , flowering locus c , enhancer , histone , genetics , gene expression , promoter
Summary Trithorax‐group proteins (TrxGs) play essential regulatory roles in chromatin modification to activate transcription. Although TrxGs have been shown to be extensively involved in the activation of developmental genes, how the specific TrxGs function in the dehydration and abscisic acid ( ABA )‐mediated modulation of downstream gene expression remains unknown. Here, we report that two evolutionarily conserved Arabidopsis thaliana TrxGs, ARABIDOPSIS TRITHORAX4 ( ATX 4) and ATX 5, play essential roles in the drought stress response. atx4 and atx5 single loss‐of‐function mutants showed drought stress‐tolerant and ABA ‐hypersensitive phenotypes during seed germination and seedling development, while the atx4 atx5 double mutant displayed further exacerbation of the phenotypes. Genome‐wide RNA ‐sequencing analyses showed that ATX 4 and ATX 5 regulate the expression of genes functioning in dehydration stress. Intriguingly, ABA ‐ HYPERSENSITIVE GERMINATION 3 ( AHG 3 ), an essential negative regulator of ABA signaling, acts genetically downstream of ATX 4 and ATX 5 in response to ABA . ATX 4 and ATX 5 directly bind to the AHG 3 locus and trimethylate histone H3 of Lys 4 (H3K4). Moreover, ATX 4 and ATX 5 occupancies at AHG 3 are dramatically increased under ABA treatment, and are also essential for RNA polymerase II (RNAPII) occupancies. Our findings reveal novel molecular functions of A. thaliana TrxGs in dehydration stress and ABA responses.