Sugar/osmoticum levels modulate differential abscisic acid-independent expression of two stress-responsive sucrose synthase genes in Arabidopsis

摘要: Sucrose synthase (Sus) is a key enzyme of sucrose metabolism. Two Sus-encoding genes (Sus1 and Sus2) from Arabidopsis thaliana were found to be profoundly differentially regulated in leaves exposed environmental stresses (cold stress, drought or O(2) deficiency). Transcript levels Sus1 increased on exposure cold drought, whereas Sus2 mRNA was induced specifically by deficiency. Both exposures the accumulation soluble sugars caused decrease leaf osmotic potential, deficiency characterized nearly complete depletion sugars. Feeding abscisic acid (ABA) detached subjecting ABA-deficient mutants stress conditions had no effect expression profiles Sus2, feeding metabolizable (sucrose glucose) non-metabolizable osmotica [poly(ethylene glycol), sorbitol mannitol] mimicked effects leaves. By using various sucrose/mannitol solutions, we demonstrated that up-regulated potential rather than an increase concentration itself. We suggest via ABA-independent signal transduction pathway related perception during stresses. In contrast, independent sugar/osmoticum effects, suggesting involvement mechanism distinct regulating expression. The differential stress-responsive regulation Sus might represent part general cellular response allocation carbohydrates acclimation processes.