Papillae formation on Arabidopsis leaf trichomes requires the function of Mediator tail subunits 2, 14, 15a, 16, and 25
Arabidopsis Mediator subunits 2, 14, 15a, 16, and 25 are required for papillae development on the trichome cell wall surface.
Arabidopsis leaf hairs exhibit raised protrusions, termed papillae, on their cell wall surfaces. Here, we show that the glassy hair mutant, glh2, exhibits trichomes with an approximate 11-fold decrease in papillae density on their surfaces in comparison to wild type. This phenotype was found to be the result of mutations in Arabidopsis Mediator subunit 16. MED16 is localized to the nucleus of trichomes, consistent with Mediator’s role in transcription. The expression patterns of the trichome development reporters, ETR2pro::GUS and GL2pro::GUS, as well as GL2 transcript levels were not altered in the glh2 mutant. Screening of available T-DNA insertion lines in other subunits of the Mediator tail module revealed glassy trichome phenotypes in med2, med14, and med15a mutants. The data suggest that the Mediator complex is required for expression of genes involved in trichome papillae development.
KeywordsCell wall Papillae Mediator Transcriptional regulation Trichome development
The authors would like to thank Dr. Heather Knight at Durham University, England, for kindly sending them 35S::GFP:MED16 seeds and the pK7WGF2 plasmid containing MED16 cDNA. They would like to acknowledge the Arabidopsis Biological Resource Center (http://abrc.osu.edu), from which they obtained T-DNA lines. Dr. Zhonglin Mou at University of Florida and Dr. Clint Chapple at Purdue University graciously sent them med14-1 & med15a, and med2-1, med3-1, med5a/med5b, & med23-4 seeds, respectively. The authors would also like to thank Dr. Martha Cook for her help with the SEM imaging. This research was supported by Illinois State University (CF, TR, and VK) and by a Weigel Grant from the Beta Lambda chapter of Phi-Sigma Biological Society awarded to CF.
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