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The A rabidopsis M ediator complex subunits MED 14/ SWP and MED 16/ SFR 6/ IEN 1 differentially regulate defense gene expression in plant immune responses
Author(s) -
Zhang Xudong,
Yao Jin,
Zhang Yanping,
Sun Yijun,
Mou Zhonglin
Publication year - 2013
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.12216
Subject(s) - arabidopsis , biology , mediator , pseudomonas syringae , mutant , transcription (linguistics) , microbiology and biotechnology , transcription factor , gene , mutation , general transcription factor , genetics , gene expression , promoter , linguistics , philosophy
Summary Pathogen infection in plants triggers large‐scale transcriptional changes, both locally and systemically. Emerging evidence suggests that the A rabidopsis M ediator complex plays a crucial role in these transcriptional changes. Mediator is highly conserved in eukaryotes, and its core comprises more than 20 subunits organized into three modules named head, middle and tail. The head and middle modules interact with general transcription factors and RNA polymerase II , whereas the tail module associates with activators, and signals through the head and middle modules to the basal transcription machinery. In Arabidopsis, three tail module subunits, MED 14, MED 15 and MED 16, have been identified. Both MED 15 and MED 16 have been implicated in plant immunity, but the role of MED 14 has not been established. Here, we report the characterization of an Arabidopsis T– DNA insertion mutant of the MED 14 gene. Similarly to the med15 and/or med16 mutations, the med14 mutation significantly suppresses salicylic acid‐induced defense responses, alters transcriptional changes induced by the avirulent bacterial pathogen P seudomonas syringae pv. tomato ( Pst ) DC 3000/ avrRpt2 , and renders plants susceptible to both Pst DC 3000/ avrRpt2 and Pst DC 3000. The med14 mutation also completely compromises biological induction of systemic acquired resistance ( SAR ), indicating that the tail module as a whole is essential for SAR . Interestingly, unlike the med16 mutation, which differentially affects expression of several SAR positive and negative regulators, med14 inhibits induction of a large group of defense genes, including both SAR positive and negative regulators, suggesting that individual subunits of the Mediator tail module employ distinct mechanisms to regulate plant immune responses.