title: PHYTOCHROME-INTERACTING FACTOR 5 (PIF5) positively regulates dark-induced senescence and chlorophyll degradation in Arabidopsis.
abstract: Darkness is a known environmental factor that induces plant senescence. Here, Phytochrome-Interacting Factors (PIFs), several bHLH transcription factors involved in plant skotomorphogenesis, were examined for their roles in the regulation of dark-induced senescence and chlorophyll breakdown in Arabidopsis thaliana. After light-grown seedlings were transferred to darkness, green leaves turned yellow, and chlorophyll contents decreased, but membrane lipid peroxidation and cell death increased in wild-type Col-0. These responses were enhanced in overexpression line PIF5OX but decreased in mutant pif5-3. Darkness significantly induced expression of several genes involved in chlorophyll breakdown, including SGR, NYC1, NOL, and PAO, as well as genes encoding for transcription factors that have been shown to be required for dark-induced senescence, including WRKY22, NAP, EIN3, EIL1, and ORE1. These effects on gene expression were also enhanced in PIF5OX but decreased in pif5-3 relative to Col-0. Further analyses using ChIP-qPCR, EMSA, and protoplast transient assays indicated that PIF5 binds to the G-box motifs in the promoters of SGR, NYC1, and ORE1 genes and stimulate their expression. Collectively, our data indicate that PIF5 is a key factor that positively regulates dark-induced senescence upstream of ORE1 and regulates chlorophyll breakdown upstream of SGR and NYC1.
authors.affiliation: Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, Gansu 730000, People's Republic of China; School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong Special Administrative Region, China.
authors.forename: Yongqiang
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu 730000, People's Republic of China.
authors.forename: Zhongjuan
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, Gansu 730000, People's Republic of China.
authors.forename: Yadi
authors.initials: Y
authors.lastname: Chen
authors.affiliation: School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong Special Administrative Region, China. Electronic address: jxhe@cuhk.edu.hk.
authors.forename: Jun-Xian
authors.initials: JX
authors.lastname: He
authors.affiliation: Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, Gansu 730000, People's Republic of China. Electronic address: yrbi@lzu.edu.cn.
authors.forename: Yurong
authors.initials: Y
authors.lastname: Bi
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics* / Q000378:metabolism; D016922:Cellular Senescence; D002734:Chlorophyll / Q000378:metabolism; D003624:Darkness; D018506:Gene Expression Regulation, Plant; D010834:Phytochrome / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D036226:Seedlings / Q000235:genetics / Q000502:physiology / Q000528:radiation effects
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D002734:Chlorophyll; D010834:Phytochrome; C497729:PIF5 protein, Arabidopsis
keywords: Arabidopsis thaliana; Chlorophyll degradation; Dark-induced senescence; PHYTOCHROME-INTERACTING FACTOR 5