Phytochrome B increases drought tolerance enhancing ABA sensitivity in Arabidopsis thaliana

GONZÁLEZ CARINA ; IBARRA SILVIA; PICCOLI PATRICIA; BOTTO JAVIER; BOCCALANDRO HERNÁN

PLANT, CELL AND ENVIRONMENT (PRINT)

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2012 vol. 35, p. 1958 - 1968

0140-7791

Phytochrome B (phyB) mediates acclimation to open environments increasing carbon gain at the expense of high water loss through a fine adjustment of morphological and physiological responses. This behavior alleviates stressful conditions generated by an excess of light but increases the chances of experiencing drought. Here we evaluated the hypothesis that phyB modulates drought tolerance in adult plants of Arabidopsis thaliana. phyB-5, phyB-1 and L.erecta (WT) adult plants were exposed to 7 or 16 d of water shortage. phyB mutants wilted before the WT, as they maintained their stomata open despite a reduction in soil water content. Although phyB-5 presented enhanced ABA levels under well-watered conditions, it was less sensitive in diminishing stomatal conductance than WT in response to ABA spraying, a treatment that induces stomatal closure. Reduced sensitivity to ABA in the phyB-5 mutant correlated with a lower expression of ABCG22, a putative ABA influx transporter, and PYL5, a soluble ABA receptor. Furthermore, the expression of RAB18 and RD29A, both typical ABA-induced genes, was lower in phyB-5 than in the WT after ABA spraying. We propose that phyB contributes to the acclimation of plants to open environments enhancing ABA sensitivity when soil water becomes a scarce resource.