ACCUMULATION OF CYTOSOLIC GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE RNA UNDER BIOLOGICAL STRESS CONDITIONS AND ELICITOR TREATMENTS IN POTATO

Plants respond to pathogen infection and environmental stress by regul ating the coordinate expression of many stress-related genes. In plant s, the expression of the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is induced under environmental stress. This work was aimed at investigating whether the expression pattern of cytosoli c GAPDH is also modulated upon infection of potato plants (Solanum tub erosum L.) with the late blight fungal agent Phytophthora infestans. N orthern blot analysis showed the accumulation of the GAPDH gene transc ripts in leaves and stems of inoculated potato plants. When tuber disc s were treated with eicosapentaenoic acid (EPA), an elicitor found in P. infestans, GAPDH gene transcripts level increased. This increase wa s parallel to that of the hydroxymethyl glutharyl coenzyme A reductase (HMGR), an enzyme involved in pathogen defense reactions. Glucans obt ained from P. infestans cell wall acts sinergistically with EPA on GAP DH and HMGR gene induction. Salicylic acid, an endogenous signal for i nducing systemic acquired resistance, was also effective in stimulatin g the GAPDH transcript accumulation in potato leaves. These experiment s suggest that related multi-component factors, which are part of both primary and secondary metabolism, are probably regulated by similar s ignal transduction pathways when they are induced under biotic or abio tic stress conditions.