title: CONSTANS-LIKE 7 (COL7) is involved in phytochrome B (phyB)-mediated light-quality regulation of auxin homeostasis.
abstract: Arabidopsis phytochrome B (phyB) is the major photoreceptor that senses the ratio of red to far-red light (R:FR) to regulate the shade-avoidance response (SAR). It has been hypothesized that altered homeostasis of phytohormones such as auxin and strigolactone is at least partially responsible for SAR, but the mechanism underlying phyB regulation of the hormonal change is not fully understood. Previously we reported that CONSTANS-LIKE 7 (COL7) enhances branching number under high R:FR but not under low R:FR, implying that COL7 may be involved in the phyB-mediated SAR. In this study, we provide evidence that COL7 reduces auxin levels in a high R:FR-dependent manner. We found that the phyB mutation suppresses the COL7-induced branching proliferation. Moreover, COL7 promotes mRNA expression of SUPERROOT 2 (SUR2), which encodes a suppressor of auxin biosynthesis, in high R:FR but not in low R:FR. Consistently with these results, deficiency of phyB suppresses the elevated transcription of SUR2 in COL7 overexpression plants grown in high R:FR. Taking these results together with data suggesting that photo-excited phyB is required for stabilization of the COL7 protein, we argue that COL7 is a critical factor linking light perception to changes in auxin level in Arabidopsis.
authors.affiliation: Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
authors.forename: Zenglin
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
authors.forename: Ronghuan
authors.initials: R
authors.lastname: Ji
authors.affiliation: Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
authors.forename: Hongyu
authors.initials: H
authors.lastname: Li
authors.affiliation: Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Zhao
authors.affiliation: Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Molecular, Cell & Developmental Biology, University of California, Los Angeles, CA 90095, USA.
authors.forename: Chentao
authors.initials: C
authors.lastname: Lin
authors.affiliation: Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China. Electronic address: liubin05@caas.cn.
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000254:growth & development / Q000378:metabolism* / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D006706:Homeostasis / Q000528:radiation effects*; D007210:Indoleacetic Acids / Q000378:metabolism*; D008027:Light; D009154:Mutation; D051939:Phytochrome B / Q000235:genetics / Q000378:metabolism*; D055550:Protein Stability / Q000528:radiation effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000528:radiation effects; D014157:Transcription Factors / Q000378:metabolism*; D015533:Transcriptional Activation / Q000528:radiation effects
chemical_list: D029681:Arabidopsis Proteins; C000595282:CONSTANS-LIKE 7 protein, Arabidopsis; D004268:DNA-Binding Proteins; D007210:Indoleacetic Acids; D012333:RNA, Messenger; D014157:Transcription Factors; D051939:Phytochrome B
keywords: COL7; SUR2; auxin homeostasis.; phyB; shade avoidance