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The Mediator kinase module serves as a positive regulator of salicylic acid accumulation and systemic acquired resistance
Author(s) -
Huang Jianhua,
Sun Yulin,
Orduna Alberto R.,
Jetter Reinhard,
Li Xin
Publication year - 2019
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.14278
Subject(s) - biology , systemic acquired resistance , kinase , cyclin dependent kinase , mutant , microbiology and biotechnology , mediator , arabidopsis , transcription factor , salicylic acid , cyclin dependent kinase 8 , transcriptional regulation , gene , genetics , signal transduction , cell cycle , notch signaling pathway
Summary In plants, the calmodulin‐binding transcription activators ( CAMTA s) are required for transcriptional regulation of abiotic and biotic stress responses. Among them, CAMTA 3 in Arabidopsis has been intensively studied and shown to function redundantly with CAMTA 1 and CAMTA 2 to negatively regulate plant immunity. The camta1/2/3 triple mutant accordingly exhibits severe dwarfism due to autoimmunity. Here, through a suppressor screen using camta1/2/3 triple mutant, we found that a mutation in Cyclin‐Dependent Kinase 8 ( CDK 8 ) partially suppresses the dwarfism and constitutive resistance phenotypes of camta1/2/3 . CDK 8 positively regulates steady‐state salicylic acid ( SA ) levels and systemic required resistance ( SAR ). The expression of SA biosynthesis genes such as ICS 1 and EDS 5 is down‐regulated in cdk8 mutants under uninfected conditions, suggesting that CDK 8 contributes to the transcriptional regulation of these SA pathway genes. Knocking out another Mediator kinase module member MED 12 yielded similar defects including decreased steady‐state SA level and compromised SAR , suggesting that the whole Mediator kinase module contributes to the transcriptional regulation of SA levels and SAR .