Primisulfuron-Tolerant Pepper : A Biochemical Basis of Tolerance

Abstract

Response of pepper (Capsicum sp.) cultivars to primisulfuron {methyl 2-[[[[[4,6-bis (difluoromethoxy)-2-pyrimidinyl] amino] carbonyl] amino] sulfonyl] benzoate} was evaluated at the whole plant and enzyme levels. Tolerant cultivars, Red Horn and Kwangbok, demonstrated 3 fold tolerance to primisulfuron in terms of plant height and dry weight compared to those of susceptible cultivars, Chamjoah and Poongchon. Acetolactate synthase (ALS) levels showed that the concentrations of primisulfuron required for 50% in vitro inhibition of ALS activity were 10-15 times greater for the tolerant cultivars compared to the susceptible ones. These data suggest that the differential ALS sensitivity may be considered for an alteration at the target site for primisulfuron tolerance. In addition, the level of tolerance by the ALS enzyme is related to observe whole plant tolerance to primisulfuron.