Trithorax-group proteins ARABIDOPSIS TRITHORAX4 (ATX4) and ATX5 function in abscisic acid and dehydration stress responses.

Abstract

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 (ATX4) and ATX5, 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 ATX4 and ATX5 regulate the expression of genes functioning in dehydration stress. Intriguingly, ABA-HYPERSENSITIVE GERMINATION 3 (AHG3), an essential negative regulator of ABA signaling, acts genetically downstream of ATX4 and ATX5 in response to ABA. ATX4 and ATX5 directly bind to the AHG3 locus and trimethylate histone H3 of Lys 4 (H3K4). Moreover, ATX4 and ATX5 occupancies at AHG3 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.

• Authors: Yutong Liu, Ai Zhang, Hao Yin, Qingxiang Meng, Xiaoming Yu, Shuangzhan Huang, Jie Wang, Rafiq Ahmad, Bao Liu, Zheng-Yi Xu
• Journal: The New phytologist (New Phytol) Vol. 217 Issue 4 Pg. 1582-1597 (03 2018) ISSN: 1469-8137 [Electronic] England
• PMID: 29250818 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Chemical References

• Arabidopsis Proteins
• Histones
• Abscisic Acid
• ATX4 protein, Arabidopsis
• ATX5 protein, Arabidopsis
• Histone-Lysine N-Methyltransferase
• Lysine

Topics

• Abscisic Acid (metabolism, pharmacology)
• Arabidopsis (drug effects, genetics, physiology)
• Arabidopsis Proteins (genetics, metabolism)
• Dehydration
• Droughts
• Gene Expression Regulation, Plant (drug effects)
• Genetic Loci
• Histone-Lysine N-Methyltransferase (genetics, metabolism)
• Histones (metabolism)
• Loss of Function Mutation (genetics)
• Lysine (metabolism)
• Methylation
• Organ Specificity (drug effects)
• Plant Development (drug effects)
• Stress, Physiological (drug effects, genetics)
• Transcription, Genetic (drug effects)