title: The Arabidopsis tandem zinc finger protein AtTZF1 affects ABA- and GA-mediated growth, stress and gene expression responses.
abstract: Tandem zinc finger (TZF) proteins are characterized by two zinc-binding CCCH motifs arranged in tandem. Human TZFs such as tristetraproline (TTP) bind to and trigger the degradation of mRNAs encoding cytokines and various regulators. Although the molecular functions of plant TZFs are unknown, recent genetic studies have revealed roles in hormone-mediated growth and environmental responses, as well as in the regulation of gene expression. Here we show that expression of AtTZF1 (AtCTH/AtC3H23) mRNA is repressed by a hexokinase-dependent sugar signaling pathway. However, AtTZF1 acts as a positive regulator of ABA/sugar responses and a negative regulator of GA responses, at least in part by modulating gene expression. RNAi of AtTZF1-3 caused early germination and slightly stress-sensitive phenotypes, whereas plants over-expressing AtTZF1 were compact, late flowering and stress-tolerant. The developmental phenotypes of plants over-expressing AtTZF1 were only partially rescued by exogenous application of GA, implying a reduction in the GA response or defects in other mechanisms. Likewise, the enhanced cold and drought tolerance of plants over-expressing AtTZF1 were not associated with increased ABA accumulation, suggesting that it is mainly ABA responses that are affected. Consistent with this notion, microarray analysis showed that over-expression of AtTZF1 mimics the effects of ABA or GA deficiency on gene expression. Notably, a gene network centered on a GA-inducible and ABA/sugar-repressible putative peptide hormone encoded by GASA6 was severely repressed by AtTZF1 over-expression. Hence AtTZF1 may serve as a regulator connecting sugar, ABA, GA and peptide hormone responses.
authors.affiliation: Department of Plant Cellular and Molecular Biology, Plant Biotechnology Center, Ohio State University, Columbus, OH 43210, USA.
authors.forename: Pei-Chi
authors.initials: PC
authors.lastname: Lin
authors.forename: Marcelo C
authors.initials: MC
authors.lastname: Pomeranz
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Jikumaru
authors.forename: Shin Gene
authors.initials: SG
authors.lastname: Kang
authors.forename: Cyrus
authors.initials: C
authors.lastname: Hah
authors.forename: Shozo
authors.initials: S
authors.lastname: Fujioka
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kamiya
authors.forename: Jyan-Chyun
authors.initials: JC
authors.lastname: Jang
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism* / Q000494:pharmacology / Q000502:physiology; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003080:Cold Temperature; D055864:Droughts; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D018525:Germination; D005875:Gibberellins / Q000378:metabolism* / Q000494:pharmacology / Q000502:physiology; D005947:Glucose / Q000378:metabolism; D006593:Hexokinase / Q000378:metabolism; D046228:Microarray Analysis; D010937:Plant Growth Regulators / Q000378:metabolism* / Q000494:pharmacology / Q000502:physiology; D030821:Plants, Genetically Modified; D034622:RNA Interference; D018749:RNA, Plant / Q000378:metabolism; D012639:Seeds / Q000254:growth & development / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology; D013312:Stress, Physiological; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D005875:Gibberellins; D010937:Plant Growth Regulators; D018749:RNA, Plant; C548151:TZF1 protein, Arabidopsis; D014157:Transcription Factors; D000040:Abscisic Acid; C007842:gibberellic acid; D006593:Hexokinase; D005947:Glucose