Transcription Factor ATAF1 in Arabidopsis Promotes Senescence by Direct Regulation of Key Chloroplast Maintenance and Senescence Transcriptional Cascades

• Published in: Plant physiology (Bethesda) Vol. 168; no. 3; pp. 1122 - 1139
• Main Authors: Garapati, Prashanth, Xue, Gang-Ping, Munné-Bosch, Sergi, Balazadeh, Salma
• Format: Journal Article
• Language: English
• Published: United States American Society of Plant Biologists 01.07.2015
• Subjects: Abscisic Acid - pharmacology; American culture; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Cellular senescence; Chlorophylls; Chloroplasts - genetics; Darkness; Gene expression regulation; Gene Expression Regulation, Plant - drug effects; Genes; Genes, Plant; Homeostasis - drug effects; Homeostasis - genetics; Hydrogen Peroxide - pharmacology; Leaves; Models, Biological; Plant cells; Plant Leaves - drug effects; Plant Leaves - genetics; Plant Leaves - growth & development; Plants; Plants, Genetically Modified; Repressor Proteins - genetics; Repressor Proteins - metabolism; Seedlings; SIGNALING AND RESPONSE; Stress, Physiological - drug effects; Stress, Physiological - genetics; Transcription factors
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.15.00567

Senescence represents a fundamental process of late leaf development. Transcription factors (TFs) play an important role for expression reprogramming during senescence; however, the gene regulatory networks through which they exert their functions, and their physiological integration, are still largely unknown. Here, we identify the Arabidopsis (Arabidopsis thaliana) abscisic acid (ABA)- and hydrogen peroxide-activated TFArabidopsis thaliana ACTIVATING FACTOR1(ATAF1) as a novel upstream regulator of senescence. ATAF1 executes its physiological role by affecting both key chloroplast maintenance and senescence-promoting TFs, namelyGOLDEN2-LIKE1(GLK1) andORESARA1(ARABIDOPSIS NAC092), respectively. Notably, while ATAF1 activatesORESARA1, it repressesGLK1expression by directly binding to their promoters, thereby generating a transcriptional output that shifts the physiological balance toward the progression of senescence. We furthermore demonstrate a key role of ATAF1 for ABA- and hydrogen peroxide-induced senescence, in accordance with a direct regulatory effect on ABA homeostasis genes, includingNINE-CIS-EPOXYCAROTENOID DIOXYGENASE3involved in ABA biosynthesis andABC TRANSPORTER G FAMILY MEMBER40, encoding an ABA transport protein. Thus, ATAF1 serves as a core transcriptional activator of senescence by coupling stress-related signaling with photosynthesis- and senescence-related transcriptional cascades.