Effect of GA, SA and JA on PIP Aquaporin Expression in Fragaria x ananassa Leaves

Aquaporins are water channels that facilitate passive water transport across inter- and intracellular membranes. They regulate water transport at cellular level. There are several types of aquaporins, but because of their abundance and subcellular location, the plasma membrane intrinsic proteins (PIPs) are thought to contribute substantially to regulating plant water relations and to participate in abiotic stress responses. The question rises which hormones are involved in signal transduction.
Fragaria x ananassa cv. Figaro plants were transferred to a watery solution containing either no hormones (control), 0.5 mM salicylic acid (SA), 0.05 mM gibberellic acid (GA) or 0.1 mM jasmonic acid (JA). During these treatments, stomata opened transiently under influence of SA and JA (less than 6 and 11 hours respectively). GA caused opening of the stomata during the first 12 hours. After 24 hours, stomata were closed in all treatments, possibly due to a lack of aeration.
Genes similar to FaPIP1;1 and FaPIP1;2 are downregulated by GA after 6h. Genes similar to FaPIP1;3 are upregulated by JA after 12h. Genes similar to FaPIP2;1 are upregulated by JA and downregulated by SA after 6h. Expression of genes similar to FaPIP2;2 does not seem to be influenced by any of the tested hormones. The responses of the different PIP aquaporins are diverse, but seem to be limited in time to 6 to 12 hours after the start of the treatment. In other species, the effect on the expression seems to vary with aquaporin, hormone concentration, tissue and duration of the treatment.