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Phytochrome A increases tolerance to high evaporative demand

IFEVA-CONICET, Facultad de Agronomía, Universidad de Buenos Aires, Buenos Aires, Argentina IBAM-CONICET, Facultad de Ciencias Agrarias, Universidad Nacional de Cuyo, Mendoza, Argentina Instituto de Ciencias Básicas, Universidad Nacional de Cuyo, Mendoza, Argentina Laboratorio de Anatomía Vegetal, Cátedra de Botánica Agrícola, Facultad de Agronomía, Universidad de Buenos Aires, Buenos Aires, Argentina.
Physiologia Plantarum (Impact Factor: 3.26). 10/2012; 146(2):228. DOI: 10.1111/j.1399-3054.2012.01625.x

ABSTRACT Stresses resulting from high transpiration demand induce adjustments in plants that lead to reductions of water loss. These adjustments, including changes in water absorption, transport and/or loss by transpiration, are crucial to normal plant development. Tomato wild type (WT) and phytochrome A mutant plants, fri1-1, were exposed to either low or high transpiration demand conditions and several morphological and physiological changes were measured during stressing conditions. Mutant plants rapidly wilted compared to WT plants after exposure to high evaporative demand. Root size and hydraulic conductivity did not show significant differences between genotypes, suggesting that water absorption and transport through this organ could not explain the observed phenotype. Moreover, stomata density was similar between genotypes, whereas transpiration and stomata conductance were both lower in mutant than in wild type plants. This was accompanied by a lower stem specific hydraulic conductivity in mutant plants than in wild type, which was associated to smaller xylem vessel number and transversal area in fri1-1 plants, producing a reduction in water supply to the leaves, rapidly reaching wilting under high evaporative demand. Phytochrome A signaling might facilitate the adjustment to environments differing widely in water evaporative demand in part through the modulation of xylem dimensions.

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    • "The mechanisms by which phytochrome influences water economy may be more or less complicated (Boccalandro et al., 2009; González et al., 2012; Sokolskaya et al., 2003). Some recent reports show that the phytochrome increases tolerance to high evaporative demand (Auge et al., 2012) and that phytochromes phyA and phyB can modulate drought stress responses (D'Amico-Damiāo et al., 2015). CONCLUSIONS 1. Direct solar irradiance in the far-red range depends strongly on atmospheric water vapour. "
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    • "However, whether the " phyA–promoter association " model is a universal mechanism for gene regulation throughout the entire genome of Arabidopsis, and whether FR influences multiple biological processes beyond anthocyanin accumulation, remain to be determined. Interestingly, recent reports have identified crosstalk networks involving phyA and numerous internal and external stimuli, such as brassinosteroid, auxin, and various stresses resulting from water loss or wounds (Robson et al., 2010; Liu et al., 2011; Auge et al., 2012; Sandhu et al., 2012). Moreover, abscisic acid (ABA) signaling interferes with phyA-dependent seed germination (Lee et al., 2012). "
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