MDP25, a novel calcium regulatory protein, mediates hypocotyl cell elongation by destabilizing cortical microtubules in Arabidopsis.
The regulation of hypocotyl elongation is important for plant growth. Microtubules play a crucial role during hypocotyl cell elongation. However, the molecular mechanism underlying this process is not well understood. In this study, we describe a novel Arabidopsis thaliana microtubule-destabilizing protein 25 (MDP25) as a negative regulator of hypocotyl cell elongation. We found that MDP25 directly bound to and destabilized microtubules to enhance microtubule depolymerization in vitro. The seedlings of mdp25 mutant Arabidopsis lines had longer etiolated hypocotyls. In addition, MDP25 overexpression resulted in significant overall shortening of hypocotyl cells, which exhibited destabilized cortical microtubules and abnormal cortical microtubule orientation, suggesting that MDP25 plays a crucial role in the negative regulation of hypocotyl cell elongation. Although MDP25 localized to the plasma membrane under normal conditions, increased calcium levels in cells caused MDP25 to partially dissociate from the plasma membrane and move into the cytosol. Cellular MDP25 bound to and destabilized cortical microtubules, resulting in their reorientation, and subsequently inhibited hypocotyl cell elongation. Our results suggest that MDP25 exerts its function on cortical microtubules by responding to cytoplasmic calcium levels to mediate hypocotyl cell elongation.
State Key Laboratory of Plant Physiology and Biochemistry, Department of Plant Sciences, College of Biological Sciences, China Agricultural University, Beijing, China.
Jiejie
J
Li
Xianling
X
Wang
Tao
T
Qin
Yan
Y
Zhang
Xiaomin
X
Liu
Jingbo
J
Sun
Yuan
Y
Zhou
Lei
L
Zhu
Ziding
Z
Zhang
Ming
M
Yuan
Tonglin
T
Mao
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D018929:Cell Culture Techniques; D049108:Cell Enlargement; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004136:Dinitrobenzenes / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant; D018546:Hypocotyl / Q000166:cytology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008870:Microtubules / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D059828:Plant Cells / Q000187:drug effects / Q000378:metabolism; D058105:Polymerization; D011485:Protein Binding; D021381:Protein Transport; D036226:Seedlings / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D016415:Sequence Alignment; D013424:Sulfanilamides / Q000494:pharmacology; D014404:Tubulin / Q000235:genetics / Q000378:metabolism; D050257:Tubulin Modulators / Q000378:metabolism
D029681:Arabidopsis Proteins; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D004136:Dinitrobenzenes; D008565:Membrane Proteins; C521040:PCaP1 protein, Arabidopsis; D013424:Sulfanilamides; D014404:Tubulin; D050257:Tubulin Modulators; C012465:oryzalin; D002118:Calcium