title: Overexpression of miR172 suppresses the brassinosteroid signaling defects of bak1 in Arabidopsis.
abstract: BRI1-Associated Receptor Kinase 1 (BAK1) is a leucine-rich repeat serine/threonine receptor-like kinase (LRR-RLK) that is involved in multiple developmental pathways, such as brassinosteroid (BR) signaling, plant immunity and cell death control in plants. Because the roundish and compact rosette leaves of bak1 mutant plants are characteristic phenotypes for deficient BR signaling, we screened genetic suppressors of bak1 according to changes in leaf shape to identify new components that may be involved in BAK1-mediated BR signaling using the activation-tagging method. Here, we report bak1-SUP1, which exhibited longer and narrower rosette leaves and an increased BR sensitivity compared with those of bak1. Analyses of the T-DNA insertional site and the gene expression that was affected by the T-DNA insertion revealed that a microRNA, namely, miR172, over-accumulates in bak1-SUP1. Detailed phenotypic analyses of bak1-SUP1 and a single mutant in which the bak1 mutation was segregated out (miR172-D) revealed that the overexpression of miR172 promotes leaf length elongation in adult plants and increases the root and hypocotyl growth during the seedling stage compared with that of wild type plants. Taken together with its increased BR sensitivity, these results suggest that miR172 regulates vegetative growth patterns by modulating BR sensitivity as well as by the previously identified developmental phase transition.
authors.affiliation: Department of Biological Science, Sookmyung Women's University, Seoul 140-742, Republic of Korea.
authors.forename: Beg Hab
authors.initials: BH
authors.lastname: Kim
authors.affiliation: Department of Life Sciences, Sogang University, Seoul 121-742, Republic of Korea.
authors.forename: Yerim
authors.initials: Y
authors.lastname: Kwon
authors.affiliation: Department of Life Sciences, Sogang University, Seoul 121-742, Republic of Korea.
authors.forename: Byeong-Ha
authors.initials: BH
authors.lastname: Lee
authors.affiliation: Department of Biological Science, Sookmyung Women's University, Seoul 140-742, Republic of Korea. Electronic address: khnam514@sookmyung.ac.kr.
authors.forename: Kyoung Hee
authors.initials: KH
authors.lastname: Nam
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D060406:Brassinosteroids / Q000378:metabolism* / Q000494:pharmacology; D035683:MicroRNAs / Q000235:genetics / Q000502:physiology*; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D060406:Brassinosteroids; D035683:MicroRNAs; C543702:Mirn172 microRNA, Arabidopsis; C463660:BAK1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases
keywords: BR signaling; BRI1-Associated Receptor Kinase 1 (BAK1); Leaf architecture; MiR172; Seedling growth