After the exposure to soil drying treatments, plants alkalize xylem sap. Xylem sap alkalization is not one a chemical signal per se, but it also facilitates the mobilization and redistribution of the phytohormone abscisic acid (ABA). Therefore, the objective of this paper was to investigate the effects of chemicalsignals on the mechanism of transpiration of isolated leaves of L. esculentum Mill. cv. Ailsa Craig (WT) and mutant flacca. In bioassays, exogenic activity of different ABA concentrations and pH were tested in both genotype of tomato in order to stimulate chemical signals occurring under drought conditions. Their effects on transpiration changes were followed in a short time intervals. Results showed thattranspiration kinetic at WT was modified, when compared media with non altered (pH5 and pH7) or altered pH (acidification and alcalisation). Such modifications are partially existed in flacca, when compared pH changed media with unchanged. Mutaul effects 10nM ABA and different pH on transpiration kinetics resulted in short and rapid stomatal closure. Similar interaction was obtained inflacca as slow phases of stomatal closure, but with a higher concentration of ABA (10mM). In drought conditions xylem sap pH was higher in leaves extract than in extracts of roots, indicating that an apoplastic pH gradient exists in WT, but not in flacca plants. So, reactions of flacca could not be only the result of lower ABA concentration, but also the result of an altered sensitivity to different pH, whichleads to decreased sensitivity to ABA.
19th Symposium of the Serbian Plant Physiology Society - Program and Abstracts, 2011
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19th Symposium of the Serbian Plant Physiology Society, 2011