UPTAKE AND DETOXIFICATION OF SALICYLIC-ACID BY VICIA-FABA AND FAGOPYRUM-ESCULENTUM

Roots of Vicia faba and Fagopyrum esculentum showed a characteristic t ri-phasic uptake of salicylic acid. During the first, short phase, abs orption was unaffected by O2 depletion, vanadate or cysteine, which su ggests a diffusion of salicylic acid into the apoplast and some penetr ation into the cytoplasm. The second phase, continuing for about 6-8 ( V. faba) and 5-8 hr (F. esculentum), was stationary and no obvious upt ake was observed. The third phase was characterized by an active uptak e. The absorbed salicylic acid was differently detoxified by the two s pecies and the resulting compounds were identified. Vicia faba glucosy lated salicylic acid to form o-beta-D-glucosylhydroxybenzoic acid, whe reas F. esculentum oxidized it to 2,5-dihydroxybenzoic acid and glucos ylated this product at the 5-OH group. The enzymes involved seemed to be induced by salicylic acid. Most of the detoxification occurred duri ng the phase of active uptake.