The Microtubule-Associated Protein MAP18 Affects ROP2 GTPase Activity during Root Hair Growth.
Establishment and maintenance of the polar site are important for root hair tip growth. We previously reported that Arabidopsis (Arabidopsis thaliana) MICROTUBULE-ASSOCIATED PROTEIN18 (MAP18) functions in controlling the direction of pollen tube growth and root hair elongation. Additionally, the Rop GTPase ROP2 was reported as a positive regulator of both root hair initiation and tip growth in Arabidopsis. Both loss of function ofROP2and knockdown ofMAP18lead to a decrease in root hair length, whereas overexpression of eitherMAP18orROP2causes multiple tips or a branching hair phenotype. However, it is unclear whether MAP18 and ROP2 coordinately regulate root hair growth. In this study, we demonstrate that MAP18 and ROP2 interact genetically and functionally. MAP18 interacts physically with ROP2 in vitro and in vivo and preferentially binds to the inactive form of the ROP2 protein. MAP18 promotes ROP2 activity during root hair tip growth. Further investigation revealed that MAP18 competes with RhoGTPase GDP DISSOCIATION INHIBITOR1/SUPERCENTIPEDE1 for binding to ROP2, in turn affecting the localization of active ROP2 in the plasma membrane of the root hair tip. These results reveal a novel function of MAP18 in the regulation of ROP2 activation during root hair growth.
State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China (E.K., M.Z., Y.Z., L.Z., Y.F.); and.|Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel (S.Y.).
Erfang
E
Kang
State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China (E.K., M.Z., Y.Z., L.Z., Y.F.); and.|Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel (S.Y.).
Mingzhi
M
Zheng
State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China (E.K., M.Z., Y.Z., L.Z., Y.F.); and.|Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel (S.Y.).
Yan
Y
Zhang
State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China (E.K., M.Z., Y.Z., L.Z., Y.F.); and.|Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel (S.Y.).
Ming
M
Yuan
State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China (E.K., M.Z., Y.Z., L.Z., Y.F.); and.|Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel (S.Y.).
Shaul
http://orcid.org/0000-0003-3264-0005
S
Yalovsky
State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China (E.K., M.Z., Y.Z., L.Z., Y.F.); and zhulei3369@cau.edu.cn.|Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel (S.Y.) zhulei3369@cau.edu.cn.
Lei
http://orcid.org/0000-0002-8056-2761
L
Zhu
State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China (E.K., M.Z., Y.Z., L.Z., Y.F.); and.|Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel (S.Y.).
Ying
Y
Fu
D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D000073658:Loss of Function Mutation; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011485:Protein Binding
D029681:Arabidopsis Proteins; D019204:GTP-Binding Proteins; D008164:Luminescent Proteins; D008869:Microtubule-Associated Proteins; C520841:MAP18 protein, Arabidopsis; C499714:AT1G20090 protein, Arabidopsis