Effects of 3,4-dihydroxybenzoic acid on tobacco (Nicotiana tabacum L.) cultured in vitro. Growth regulation in callus and organ cultures

Thr influence of 3,4-dihydroxybenzoic acid (protocatechuic acid), a natural ly occurring benzoic acid derivative, on tobacco (Nicotiana tabacum L.) cel l and tissue cultures was examined. The response to 0.1, 10 and 1000 muM 3, 4-dihydroxybenzoic was tested with regards to cell proliferation in leaf ex plants, callus growth and shoot formation. Effects on shoot and root growth in micropropagated plants were also analysed. The highest concentration of 3,4-dihydroxybenzoic acid strongly inhibited the proliferation of leaf tis sues, callus growth, shoot regeneration an root growth in micropropagated p lants. On the contrary, the lowest concentration (0.1 muM) showed auxin-lik e activity by stimulating cell dedifferentiation, callus induction and root ing of leaf tissues. The presence of auxins and cytokinins in the media con trasted 3,4-dihydroxybenzoic acid inhibition of callus growth at all tested concentrations.