title: Arabidopsis microtubule destabilizing protein40 is involved in brassinosteroid regulation of hypocotyl elongation.
abstract: The brassinosteroid (BR) phytohormones play crucial roles in regulating plant cell growth and morphogenesis, particularly in hypocotyl cell elongation. The microtubule cytoskeleton is also known to participate in the regulation of hypocotyl elongation. However, it is unclear if BR regulation of hypocotyl elongation involves the microtubule cytoskeleton. In this study, we demonstrate that BRs mediate hypocotyl cell elongation by influencing the orientation and stability of cortical microtubules. Further analysis identified the previously undiscovered Arabidopsis thaliana microtubule destabilizing protein40 (MDP40) as a positive regulator of hypocotyl cell elongation. Brassinazole-resistant1, a key transcription factor in the BR signaling pathway, directly targets and upregulates MDP40. Overexpression of MDP40 partially rescued the shorter hypocotyl phenotype in BR-deficient mutant de-etiolated-2 seedlings. Reorientation of the cortical microtubules in the cells of MDP40 RNA interference transgenic lines was less sensitive to BR. These findings demonstrate that MDP40 is a key regulator in BR regulation of cortical microtubule reorientation and mediates hypocotyl growth. This study reveals a mechanism involving BR regulation of microtubules through MDP40 to mediate hypocotyl cell elongation.
authors.affiliation: State Key Laboratory of Plant Physiology and Biochemistry, Department of Plant Sciences, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Xianling
authors.initials: X
authors.lastname: Wang
authors.forename: Jin
authors.initials: J
authors.lastname: Zhang
authors.forename: Ming
authors.initials: M
authors.lastname: Yuan
authors.forename: David W
authors.initials: DW
authors.lastname: Ehrhardt
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Wang
authors.forename: Tonglin
authors.initials: T
authors.lastname: Mao
mesh_terms: D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D060406:Brassinosteroids / Q000378:metabolism*; D004268:DNA-Binding Proteins; D018546:Hypocotyl / Q000254:growth & development* / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008870:Microtubules / Q000378:metabolism / Q000648:ultrastructure; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D010641:Phenotype; D015854:Up-Regulation
chemical_list: D029681:Arabidopsis Proteins; C454444:BZR1 protein, Arabidopsis; D060406:Brassinosteroids; D004268:DNA-Binding Proteins; C581737:MDP40 protein, Arabidopsis; D008869:Microtubule-Associated Proteins; D009687:Nuclear Proteins