Herbicide Resistant Weeds

In vitro cultured cocklebur (Xanthium strumarium L.) responses to dimercaptopropanesulfonic acid and monosodium methanearsonate.

Ellis, J. P. and N. D. Camper. 1995. In vitro cultured cocklebur (Xanthium strumarium L.) responses to dimercaptopropanesulfonic acid and monosodium methanearsonate. Journal of Plant Growth Regulation. 14: 9-13.

The herbicidal effect of dimercaptopropanesulfonic acid (DMPS) and monosodium methanearsonate (MSMA) on the growth of in vitro grown cocklebur (Xanthium strumarium) shoot and callus tissues was investigated. Lateral and terminal shoots were grown on basal Murashige and Skoog medium containing 6.25 mg litre-1 (0.0428 mM) MSMA alone and with various concentrations of DMPS. Callus was cultured on basal callus medium also containing 6.25 mg litre-1 MSMA alone and an equimolar concentration of DMPS. Shoot injury symptoms, dry root weight, and fresh weight of callus were recorded. Susceptible cocklebur shoots showed severe discoloration and death when treated with MSMA. Resistant shoots and cultured shoot tips were not adversely affected. DMPS alone did not inhibit the growth of these tissues. Callus induced from susceptible tissue was inhibited by MSMA and DMPS alone. In all concentrations of DMPS and MSMA tested, DMPS did not counteract the MSMA response. Thus, the pentavalent form of arsenic in MSMA was not reduced to the trivalent form by the plant and hence it is suggested that it is not involved in the mechanism of action.