Functional analysis of the Arabidopsis PLDZ2 promoter reveals an evolutionarily conserved low-Pi-responsive transcriptional enhancer element. J Exp Bot

Laboratorio Nacional de Genómica para la Biodiversidad del Centro de Investigación y de Estudios Avanzados del IPN., Irapuato Guanajuato, Mexico.
Journal of Experimental Botany (Impact Factor: 5.53). 12/2011; 63(5):2189-202. DOI: 10.1093/jxb/err446
Source: PubMed


Plants have evolved a plethora of responses to cope with phosphate (Pi) deficiency, including the transcriptional activation of a large set of genes. Among Pi-responsive genes, the expression of the Arabidopsis phospholipase DZ2 (PLDZ2) is activated to participate in the degradation of phospholipids in roots in order to release Pi to support other cellular activities. A deletion analysis was performed to identify the regions determining the strength, tissue-specific expression, and Pi responsiveness of this regulatory region. This study also reports the identification and characterization of a transcriptional enhancer element that is present in the PLDZ2 promoter and able to confer Pi responsiveness to a minimal, inactive 35S promoter. This enhancer also shares the cytokinin and sucrose responsive properties observed for the intact PLDZ2 promoter. The EZ2 element contains two P1BS motifs, each of which is the DNA binding site of transcription factor PHR1. Mutation analysis showed that the P1BS motifs present in EZ2 are necessary but not sufficient for the enhancer function, revealing the importance of adjacent sequences. The structural organization of EZ2 is conserved in the orthologous genes of at least eight families of rosids, suggesting that architectural features such as the distance between the two P1BS motifs are also important for the regulatory properties of this enhancer element.

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    • "Environmental stresses, including P and N deprivation, drought, and high salinity, are primary limiting factors in plant growth, plant development, and crop productivities worldwide. To cope with these challenges, plants have evolved intricate molecular networks, consequently developing distinct adaptive responses via biochemical, physiological, and morphological changes (Bohnert et al., 1995; Amiour et al., 2012; Oropeza-Aburto et al., 2012; Quilleré et al., 2012). "
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    ABSTRACT: Establishing crop cultivars with strong tolerance to P and N deprivation, high salinity, and drought is an effective way to improve crop yield and promote sustainable agriculture worldwide. A vacuolar H+-pyrophosphatase (V-H+-PPase) gene in wheat (TaVP) was functionally characterized in this study. TaVP cDNA is 2586-bp long and encodes a 775-amino-acid polypeptide that contains 10 conserved membrane-spanning domains. Transcription of TaVP was upregulated by inorganic phosphate (Pi) and N deprivation, high salinity, and drought. Transgene analysis revealed that TaVP overexpression improved plant growth under normal conditions and specifically under Pi and N deprivation stresses, high salinity, and drought. The improvement of growth of the transgenic plants was found to be closely related to elevated V-H+-PPase activities in their tonoplasts and enlarged root systems, which possibly resulted from elevated expression of auxin transport-associated genes. TaVP-overexpressing plants showed high dry mass, photosynthetic efficiencies, antioxidant enzyme activities, and P, N, and soluble carbohydrate concentrations under various growth conditions, particularly under the stress conditions. The transcription of phosphate and nitrate transporter genes was not altered in TaVP-overexpressing plants compared with the wild type, suggesting that high P and N concentrations regulated by TaVP were caused by increased root absorption area instead of alteration of Pi and NO3 − acquisition kinetics. TaVP is important in the tolerance of multiple stresses and can serve as a useful genetic resource to improve plant P- and N-use efficiencies and to increase tolerance to high salinity and drought.
    Journal of Experimental Botany 02/2014; 65(2):683-96. DOI:10.1093/jxb/ert442 · 5.53 Impact Factor
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    • "A pldζ2-KO (knock-out) mutant showed reduced clathrin-dependent PIN2 internalization and reduced primary root bending (Galvan-Ampudia et al., 2013). Expression of PLDζ2 increased under low phosphate availability (Oropeza-Aburto et al., 2011) and the pldζ2-KO showed increased root hair growth when deprived of phosphate (Cruz-Ramirez et al., 2006). In accordance, less PA was formed in low phosphate conditions in the pldζ1/2 double mutant (Li et al., 2006a) and this mutant showed reduced lateral root and increased primary root growth in low phosphate conditions (Li et al., 2006b). "
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    ABSTRACT: Adequate water supply is of utmost importance for growth and reproduction of plants. In order to cope with water deprivation, plants have to adapt their development and metabolism to ensure survival. To maximize water use efficiency, plants use a large array of signaling mediators such as hormones, protein kinases, and phosphatases, Ca(2) (+), reactive oxygen species, and low abundant phospholipids that together form complex signaling cascades. Phosphatidic acid (PA) is a signaling lipid that rapidly accumulates in response to a wide array of abiotic stress stimuli. PA formation provides the cell with spatial and transient information about the external environment by acting as a protein-docking site in cellular membranes. PA reportedly binds to a number of proteins that play a role during water limiting conditions, such as drought and salinity and has been shown to play an important role in maintaining root system architecture. Members of two osmotic stress-activated protein kinase families, sucrose non-fermenting 1-related protein kinase 2 and mitogen activated protein kinases were recently shown bind PA and are also involved in the maintenance of root system architecture and salinity stress tolerance. In addition, PA regulates several proteins involved in abscisic acid-signaling. PA-dependent recruitment of glyceraldehyde-3-phosphate dehydrogenase under water limiting conditions indicates a role in regulating metabolic processes. Finally, a recent study also shows the PA recruits the clathrin heavy chain and a potassium channel subunit, hinting toward additional roles in cellular trafficking and potassium homeostasis. Taken together, the rapidly increasing number of proteins reported to interact with PA implies a broad role for this versatile signaling phospholipid in mediating salt and water stress responses.
    Frontiers in Plant Science 12/2013; 4:525. DOI:10.3389/fpls.2013.00525 · 3.95 Impact Factor
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    • "In the promoter of the Arabidopsis phospholipase DZ2 gene (PLDZ2, At3g05630), apart from five P1BS copies, elements such as SRE (sugar-repressive element) have been found. A 65-bp promoter fragment spanning two of the P1BS motifs (the EZ2 region) has been identified as particularly important for the Pi-limitation response but strong induction also required sucrose and was negatively affected by cytokinins (Oropeza-Aburto et al., 2012). Exactly how the information carried by the P1BS elements and by the various sugar and hormone responsive promoter elements is integrated by the MYB-CC TFs PHR1 and PHL1 and possibly others is still unknown. "
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    ABSTRACT: Inorganic phosphate (Pi) is an easily accessible form of phosphorus for plants. Plant Pi uptake is usually limited however by slow Pi diffusion through the soil which strongly adsorps phosphate species. Plants have developed mechanisms to increase Pi availability. There are also abiotic (phosphate level) and biotic (e.g., mycorrhizal) factors regulating the expression of Pi-responsive genes. Transcription factors binding to the promoters of Pi-responsive genes activate different pathways of Pi transport, distribution, and homeostasis maintenance. Pi metabolism involves not only functional proteins but also microRNAs and other non-coding RNAs.
    Frontiers in Plant Science 03/2012; 3:58. DOI:10.3389/fpls.2012.00058 · 3.95 Impact Factor
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