Arabidopsis HOOKLESS1 Regulates Responses to Pathogens and Abscisic Acid through Interaction with MED18 and Acetylation of WRKY33 and ABI5 Chromatin.
Arabidopsis thaliana HOOKLESS1 (HLS1) encodes a putative histone acetyltransferase with known functions in seedling growth. Here, we show that HLS1 regulates plant responses to pathogens and abscisic acid (ABA) through histone acetylation at chromatin of target loci. The hls1 mutants show impaired responses to bacterial and fungal infection, accelerated senescence, and impaired responses to ABA. HLS1 modulates the expression of WRKY33 and ABA INSENSITIVE5 (ABI5), known regulators of pathogen and ABA responses, respectively, through direct association with these loci. Histone 3 acetylation (H3Ac), a positive mark of transcription, at WRKY33 and ABI5 requires HLS1 function. ABA treatment and pathogen infection enhance HLS1 recruitment and H3Ac at WRKY33. HLS1 associates with Mediator, a eukaryotic transcription coregulatory complex, through direct interaction with mediator subunit 18 (MED18), with which it shares multiple functions. HLS1 recruits MED18 to the WRKY33 promoter, boosting WKRY33 expression, suggesting the synergetic action of HLS1 and MED18. By contrast, MED18 recruitment to ABI5 and transcriptional activation are independent of HLS1. ABA-mediated priming of resistance to fungal infection was abrogated in hls1 and wrky33 mutants but correlated with ABA-induced HLS1 accumulation. In sum, HLS1 provides a regulatory node in pathogen and hormone response pathways through interaction with the Mediator complex and important transcription factors.
Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907.
Chao-Jan
CJ
Liao
National Key Laboratory of Crop Genetics Improvement, Huazhong Agricultural University, Wuhan 430070, China.
Zhibing
0000-0001-6114-388X
Z
Lai
Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907.
Sanghun
S
Lee
Division of Applied Life Sciences (BK 21 Program), Gyeongsang National University, Jinju City 660-701, Korea.
Dae-Jin
0000-0002-3638-6043
DJ
Yun
Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907 mengiste@purdue.edu.
Tesfaye
T
Mengiste
D000040:Abscisic Acid / Q000378:metabolism*; D000107:Acetylation; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D056892:Mediator Complex / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
C409743:ABI5 protein, Arabidopsis; D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D002843:Chromatin; C582268:MED18 protein, Arabidopsis; D056892:Mediator Complex; D014157:Transcription Factors; C517860:WRKY33 protein, Arabidopsis; C530672:At4g37580 protein, Arabidopsis; D000040:Abscisic Acid