CHITOSAN-INDUCED ANTHRAQUINONE SYNTHESIS IN Rubia tinctorum INVOLVES MAPK ACTIVATION AND INTRACELLULAR CALCIUM MOBILIZATION

VASCONSUELO, A; PICCOTO; GIULIETTI, AM; BOLAND R.

Bariloche

Congreso; XXXIX Reunion Anual de la Sociedad Argentina de Investigaciones en Bioquimica y Biologia Molecular - SAIB; 2003

Plants have acquired economical importance due to the synthesis of secondary metabolites, but the levels produced in vitro are generally too low for commercial applications. Elicitation with chitosan (200 mg/l) significantly stimulated (≅100%) anthraquinone (Aq) synthesis in R. tinctorum cultures. The elicitor¡¯s action could be blocked with 1 mM BAPTA-AM but not by 1 mM EGTA. When elicitation was performed in a free- calcium medium, Aq levels were ~ 10 % higher in comparison to a medium containing calcium. Inhibitors of Ca2+ release from inner stores such as 15 ¨¬M 2-APB, 50 mM caffeine, 30 ¦ÌM ruthenium red, 0.3 mM dantrolene, 100 ¨¬M neomycin and 10 ¦ÌM U73122 abolished elicitation. Chitosan rapidly (7 min) stimulated MAPK, the enzyme remaining active at least for 60 min. This activation was blocked by BAPTA-AM and the calcium modulators mentioned above; however EGTA did not affect MAPK activity. These results show that chitosan elicitation involves MAPK activation and is dependent on intracellular but not on extracellular calcium.