title: Clathrin-Mediated Auxin Efflux and Maxima Regulate Hypocotyl Hook Formation and Light-Stimulated Hook Opening in Arabidopsis.
abstract: The establishment of auxin maxima by PIN-FORMED 3 (PIN3)- and AUXIN RESISTANT 1/LIKE AUX1 (LAX) 3 (AUX1/LAX3)-mediated auxin transport is essential for hook formation in Arabidopsis hypocotyls. Until now, however, the underlying regulatory mechanism has remained poorly understood. Here, we show that loss of function of clathrin light chain CLC2 and CLC3 genes enhanced auxin maxima and thereby hook curvature, alleviated the inhibitory effect of auxin overproduction on auxin maxima and hook curvature, and delayed blue light-stimulated auxin maxima reduction and hook opening. Moreover, pharmacological experiments revealed that auxin maxima formation and hook curvature in clc2 clc3 were sensitive to auxin efflux inhibitors 1-naphthylphthalamic acid and 2,3,5-triiodobenzoic acid but not to the auxin influx inhibitor 1-naphthoxyacetic acid. Live-cell imaging analysis further uncovered that loss of CLC2 and CLC3 function impaired PIN3 endocytosis and promoted its lateralization in the cortical cells but did not affect AUX1 localization. Taken together, these results suggest that clathrin regulates auxin maxima and thereby hook formation through modulating PIN3 localization and auxin efflux, providing a novel mechanism that integrates developmental signals and environmental cues to regulate plant skotomorphogenesis and photomorphogenesis.
authors.affiliation: College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, China.
authors.forename: Qinqin
authors.initials: Q
authors.lastname: Yu
authors.affiliation: College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Biological Sciences, NUS Centre for BioImaging Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore.
authors.forename: Juan
authors.initials: J
authors.lastname: Wang
authors.affiliation: College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Yan
authors.affiliation: College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Wang
authors.affiliation: Department of Biological Sciences, NUS Centre for BioImaging Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore.
authors.forename: Jian
authors.initials: J
authors.lastname: Xu
authors.affiliation: College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, China. Electronic address: jwpan@zjnu.cn.
authors.forename: Jianwei
authors.initials: J
authors.lastname: Pan
mesh_terms: D017360:Arabidopsis / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000378:metabolism; D002966:Clathrin / Q000378:metabolism*; D018546:Hypocotyl / Q000254:growth & development*; D007210:Indoleacetic Acids / Q000378:metabolism*; D008027:Light
chemical_list: D029681:Arabidopsis Proteins; D002966:Clathrin; D007210:Indoleacetic Acids; C449300:PIN3 protein, Arabidopsis
keywords: Arabidopsis; auxin maxima; clathrin; hook formation; hypocotyl