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The MED 7 subunit paralogs of Mediator function redundantly in development of etiolated seedlings in Arabidopsis
Author(s) -
Kumar Koppolu Raja Rajesh,
Blomberg Jeanette,
Björklund Stefan
Publication year - 2018
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.14052
Subject(s) - arabidopsis , brassinosteroid , biology , etiolation , hypocotyl , microbiology and biotechnology , agamous , auxin , genetics , gene , phenotype , rna interference , arabidopsis thaliana , complementation , mutant , transcriptome , gene expression , botany , rna , biochemistry , enzyme
Summary MED 7 is a subunit of the Mediator middle module and is encoded by two paralogs in Arabidopsis. We generated MED 7 silenced lines using RNA i to study its impact on Arabidopsis growth and development. Compared with wild type, etiolated seedlings of the MED 7 silenced lines exhibited reduced hypocotyl length caused by reduced cell elongation when grown in the dark. The hypocotyl length phenotype was rescued by exogenously supplied brassinosteroid. In addition, MED 7 silenced seedlings exhibited defective hook opening in the dark as well as defective cotyledon expansion in the presence of the brassinosteroid inhibitor brassinazole. Whole transcriptome analysis on etiolated seedlings using RNA sequencing revealed several genes known to be regulated by auxin and brassinosteroids, and a broad range of cell wall‐related genes that were differentially expressed in the MED 7 silenced lines. This was especially evident for genes involved in cell wall extension and remodeling, such as EXPANSIN s and XTH s. Conditional complementation with each MED7 paralog individually restored the hypocotyl phenotype as well as the gene expression defects. Additionally, conditional expression of MED 7 had no effects that were independent of the Mediator complex on the observed phenotypes. We concluded that the MED 7 paralogs function redundantly in regulating genes required for the normal development of etiolated Arabidopsis seedlings.