A novel mitochondrial DnaJ/Hsp40 family protein BIL2 promotes plant growth and resistance against environmental stress in brassinosteroid signaling

• Published in: Planta 2013-06, Vol.237 (6), p.1509-1525
• Main Authors: Bekh-Ochir, Davaapurev, Shimada, Setsuko, Yamagami, Ayumi, Kanda, Satomi, Ogawa, Kenji, Nakazawa, Miki, Matsui, Minami, Sakuta, Masaaki, Osada, Hiroyuki, Asami, Tadao, Nakano, Takeshi
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - biosynthesis; Agriculture; Amino Acid Sequence; Arabidopsis - drug effects; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; ATP; Biomedical and Life Sciences; Biosynthesis; Brassinosteroids; Brassinosteroids - metabolism; Ecology; Environment; Environmental stress; Forestry; Gene expression; Gene Expression Profiling; Gene expression regulation; Gene Expression Regulation, Plant - drug effects; Gene Expression Regulation, Plant - radiation effects; Genes, Plant - genetics; Genetics; Hormones; HSP40 Heat-Shock Proteins - genetics; HSP40 Heat-Shock Proteins - metabolism; Hypocotyls; Life Sciences; Light; Mitochondria; Mitochondria - drug effects; Mitochondria - metabolism; Mitochondria - radiation effects; Molecular Sequence Data; Mutation - genetics; Organ Specificity - drug effects; Organ Specificity - genetics; Organ Specificity - radiation effects; Original; Original Article; Phenotype; Phenotypes; Plant Development - drug effects; Plant Development - genetics; Plant Development - radiation effects; Plant growth; Plant Sciences; Plants; RNA Interference - drug effects; RNA Interference - radiation effects; Salt Tolerance - drug effects; Salt Tolerance - genetics; Salt Tolerance - radiation effects; Seedlings; Signal Transduction - drug effects; Signal Transduction - genetics; Signal Transduction - radiation effects; Sodium Chloride - pharmacology; Steroid hormones; Stress, Physiological - drug effects; Stress, Physiological - genetics; Stress, Physiological - radiation effects
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s00425-013-1859-3

Plant steroid hormones, brassinosteroids, are essential for growth, development and responses to environmental stresses in plants. Although BR signaling proteins are localized in many organelles, i.e., the plasma membrane, nuclei, endoplasmic reticulum and vacuole, the details regarding the BR signaling pathway from perception at the cellular membrane receptor BRASSINOSTEROID INSENSITIVE 1 (BRI1) to nuclear events include several steps. Brz (Brz220) is a specific inhibitor of BR biosynthesis. In this study, we used Brz-mediated chemical genetics to identify Brz-insensitive-long hypocotyls 2-ID (bil2-1D). The BIL2 gene encodes a mitochondrial-localized DnaJ/Heat shock protein 40 (DnaJ/Hsp40) family, which is involved in protein folding. BIL2-overexpression plants (BIL2-OX) showed cell elongation under Brz treatment, increasing the growth of plant inflorescence and roots, the regulation of BR-responsive gene expression and suppression against the dwarfed BRI1-deficient mutant. BIL2-OX also showed resistance against the mitochondrial ATPase inhibitor oligomycin and higher levels of exogenous ATP compared with wild-type plants. BIL2 participates in resistance against salinity stress and strong light stress. Our results indicate that BIL2 induces cell elongation during BR signaling through the promotion of ATP synthesis in mitochondria.