Arabidopsis SAURs are critical for differential light regulation of the development of various organs.
During deetiolation of Arabidopsis seedlings, light promotes the expansion of cotyledons but inhibits the elongation of hypocotyls. The mechanism of this differential regulation of cell enlargement is unclear. Our organ-specific transcriptomic analysis identified 32 Small Auxin Up RNA (SAUR) genes whose transcripts were light-induced in cotyledons and/or repressed in hypocotyls. We therefore named these SAURs as lirSAURs Both overexpression and mutation analyses demonstrated that lirSAURs could promote cotyledon expansion and opening and enhance hypocotyl elongation, possibly by inhibiting phosphatase activity of D-clade type 2C protein phosphatases (PP2C-Ds). Light reduced auxin levels to down-regulate the expression of lirSAURs in hypocotyls. Further, phytochrome-interacting factors (PIFs) were shown to directly bind the genes encoding these SAURs and differentially regulate their expression in cotyledons and hypocotyls. Together, our study demonstrates that light mediates auxin levels and PIF stability to differentially regulate the expression of lirSAURs in cotyledons and hypocotyls, and these lirSAURs further mediate the differential growth of these two organs.
State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agriculture Sciences and School of Life Sciences, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China;
Ning
N
Sun
State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agriculture Sciences and School of Life Sciences, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China;
Jiajun
J
Wang
State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agriculture Sciences and School of Life Sciences, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China;
Zhaoxu
Z
Gao
State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agriculture Sciences and School of Life Sciences, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China;
Jie
J
Dong
State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agriculture Sciences and School of Life Sciences, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China;
Hang
H
He
Department of Biology, Wilkes University, Wilkes-Barre, PA 18766;
William
W
Terzaghi
Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520-8104.
Ning
N
Wei
State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agriculture Sciences and School of Life Sciences, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China; deng@pku.edu.cn chenhaodong@pku.edu.cn.
Xing Wang
XW
Deng
State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agriculture Sciences and School of Life Sciences, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China; deng@pku.edu.cn chenhaodong@pku.edu.cn.
Haodong
H
Chen
D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018546:Hypocotyl / Q000235:genetics; D007210:Indoleacetic Acids / Q000378:metabolism; D008027:Light; D009154:Mutation / Q000187:drug effects; D036226:Seedlings / Q000235:genetics
D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids
PIFs; SAURs; auxin; light signal; seedling development