Genetic analysis of Arabidopsis GATA transcription factor gene family reveals a nitrae-inducible member important for chlorophyll synthesis and glucose sensitivity

Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
The Plant Journal (Impact Factor: 5.97). 12/2005; 44(4):680-92. DOI: 10.1111/j.1365-313X.2005.02568.x
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The Arabidopsis GATA transcription factor family has 30 members, the biological function of most of which is poorly understood. Homozygous T-DNA insertion lines for 23 of the 30 members were identified and analyzed. Genetic screening of the insertion lines in defined growth conditions revealed one line with an altered phenotype, while the other lines showed no obvious change. This line, SALK_001778, has a T-DNA insertion in the second exon of At5g56860 which prevents the expression of the GATA domain. Genetic analysis of the mutant demonstrated that the phenotypic change is caused by a single gene effect and is recessive to the wild-type allele. In wild-type plants, the expression of At5g56860 is shoot-specific, occurs at an early stage of development and is inducible by nitrate. Loss of expression of At5g56860 in the loss-of-function mutant plants resulted in reduced chlorophyll levels. A transcript profiling experiment revealed that a considerable proportion of genes downregulated in the loss-of-function mutants are involved in carbon metabolism and At5g56860 is thus designated GNC (GATA, nitrate-inducible, carbon metabolism-involved). gnc mutants with no GNC expression are more sensitive to exogenous glucose, and two hexose transporter genes, with a possible connection to glucose signaling, are significantly downregulated, while GNC over-expressing transgenic plants upregulate their expression and are less sensitive to exogenous glucose. These observations suggest a function for GNC in regulating carbon and nitrogen metabolism.

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Available from: Yong-Mei Bi, Nov 20, 2014
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    • "A second example from the Rothstein laboratory is based on work initiated in 2002. This work involved analysing GATA transcription factor mutants in Arabidopsis and the identification of one that we called GNC (for GATA-nitrate regulatedcarbon metabolism involved; Bi et al., 2005; reviewed in Kant et al., 2011). GNC and a paralogue gene called CGA-1 both modulate the level of chlorophyll and chloroplast number, particularly under nitrogen limitation conditions (Hudson et al., 2011). "
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    ABSTRACT: It has been 30 years since the first transformation of a gene into a plant species, and since that time a number of biotechnology products have been developed, with the most important being insect- and herbicide-resistant crops. The development of second-generation products, including nutrient use efficiency and tolerance to important environmental stressors such as drought, has, up to this time, been less successful. This is in part due to the inherent complexities of these traits and in part due to limitations in research infrastructure necessary for public sector researchers to test their best ideas. Here we discuss lessons from previous work in the generation of the first-generation traits, as well as work from our labs and others on identifying genes for nitrogen use efficiency. We then describe some of the issues that have impeded rapid progress in this area. Finally, we propose the type of public sector organization that we feel is necessary to make advances in important second-generation traits such as nitrogen use efficiency.
    Journal of Experimental Botany 06/2014; 65(19). DOI:10.1093/jxb/eru236 · 5.53 Impact Factor
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    • "CGA1 was regulated by light, nitrogen, cytokinin, and gibberellic acid, and modulated nitrogen assimilation, chloroplast development, and starch production (Bi et al., 2005; Naito et al., 2007; Mara and Irish, 2008; Richter et al., 2010; Hudson et al., 2011); CGA1 play a key role in chloroplast development, growth, and divison in Arabidopsis (Chiang et al., 2012) AP2-EREBP At4g34410 RRTF1 (redox-responsive transcription factor 1) RTF1 is involved in redox homeostasis under high light stress (Khandelwal et al., 2008) AP2-EREBP At5g05410 DREB2A (dehydration-responsive element-binding protein 2A) DREB2A is involved in dehydrationresponsive gene expression and overexpression of an active form of DREB2A results in significant stress tolerance to dehydration and significant growth retardation (Sakuma et al., 2006) C2H2 At5g59820 ZAT12 Zat12 plays a central role in reactive oxygen and abiotic stress signalling in Arabidopsis and overexpression of Zat12 in Arabidopsis results in the enhanced expression of oxidative-and light stress-response transcripts (Davletova et al., 2005) Downregulated under low CO 2 C2C2-CO-like At1g49130 COL8 (CONSTANS-LIKE 8) Zinc finger (B-box type) family protein SBP At2g33810 SPL3 (SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 3) SPL3 is involved in regulation of flowering and vegetative phase change (Cardon et al., 1997; Wu and Poethig, 2006; Yamaguchi et al., 2009) C2C2-CO-like At4g27310 BBX28 Zinc finger (B-box type) family protein G2-like At5g44190 GLK2 (Golden2-like 2) GLK2 is required for normal chloroplast development (Fitter et al., 2002); GLK2 together with GLK1 optimize photosynthetic capacity by integrating responses to variable enironmental and endogenous cues (Waters et al., 2009) MADS At5g62165 AGL42 (AGAMOUS-LIKE 42) AGL42 is involved in the floral transition and RNAi-directed downregulation of AGL24 results in late flowering (Yu et al., 2002) a mechanism to allow for greater accumulation of stored reserves that could be allocated to reproduction, resulting in increased fitness under low CO 2 (Sage and Coleman, 2001; Ward, 2005). Many studies have shown that atmospheric CO 2 concentration negatively regulates stomatal density (Woodward, 1987; Beerling et al., 2001; Franks and Beerling, 2009; Doheny- Adams et al., 2012; Franks et al., 2012). "
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    ABSTRACT: The responses of long-term growth of plants under elevated CO2 have been studied extensively. Comparatively, the responses of plants to subambient CO2 concentrations have not been well studied. This study aims to investigate the responses of the model C3 plant, Arabidopsis thaliana, to low CO2 at the molecular level. Results showed that low CO2 dramatically decreased biomass productivity, together with delayed flowering and increased stomatal density. Furthermore, alteration of thylakoid stacking in both bundle sheath and mesophyll cells, upregulation of PEPC and PEPC-K together with altered expression of a number of regulators known involved in photosynthesis development were observed. These responses to low CO2 are discussed with regard to the fitness of C3 plants under low CO2. This work also briefly discusses the relevance of the data to C4 photosynthesis evolution.
    Journal of Experimental Botany 05/2014; 65(13). DOI:10.1093/jxb/eru193 · 5.53 Impact Factor
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    • "The GATA family of transcription factors exhibits a significant degree of conservation between the dicot model organism Arabidopsis and rice, a monocot cereal with many memberretaining paralogs following genome duplication events (Reyes et al., 2004). In Arabidopsis, the expression patterns of Arabidopsis CGA1 as well as the paralogous transcription factor GATA, NITRATE-INDUCIBLE, CARBON METABOLISM-INVOVLED (GNC) have been well documented in recent years (Bi et al., 2005; Manfield et al., 2007; Naito et al., 2007; Mara and Irish, 2008; Richter et al., 2010; Hudson et al., 2011). Both are primarily expressed in green tissues and follow circadianregulated expression patterns (Manfield et al., 2007; Naito et al., 2007; Mara and Irish, 2008). "
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    ABSTRACT: Chloroplast biogenesis has been well documented in higher plants, yet the complex methods used to regulate chloroplast activity under fluctuating environmental conditions are not well understood. In rice (Oryza sativa), the CYTOKININ-RESPONSIVE GATA TRANSCRIPTION FACTOR 1 (Cga1) shows increased expression following light, nitrogen and cytokinin treatments, while darkness and gibberellin reduce expression. Strong overexpression of Cga1 produces dark green, semi-dwarf plants with reduced tillering; whereas RNAi knock-down results in reduced chlorophyll and increased tillering. Co-expression, microarray and real-time expression analyses demonstrate a correlation between Cga1 expression and the expression of important nuclear-encoded, chloroplast-localized genes. Constitutive Cga1 overexpression increases both chloroplast biogenesis and starch production, but also results in delayed senescence and reduced grain filling. Growing the transgenic lines under different nitrogen regimes indicates potential agricultural applications for Cga1, including manipulation of biomass, chlorophyll/chloroplast content and harvest index. These results indicate a conserved mechanism by which Cga1 regulates chloroplast development in higher plants.
    Plant physiology 04/2013; 162(1). DOI:10.1104/pp.113.217265 · 6.84 Impact Factor
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