Effects of colchicine and lumicolchicine on hypocotyl elongation, respiration rates and microtubules in gibberellic-acid-treated lettuce seedlings.

Gibberellic-acid (GA3)-induced hypocotyl elongation of intact lettuce (Lactuca sativa L.) seedlings was inhibited by colchicine (4×10(-4) M) but not by lumicolchicine (4×10(-4) M). In excised lettuce hypocotyls, GA3 (10(-5) M) increased respiration over water controls, while both colchicine and lumicolchicine alone, or in combination with GA3, reduced respiration. Microtubules were present in the hypocotyls of lumicolchicine-treated seedlings but absent in those treated with colchicine. It is suggested that lumicolchicine is a useful drug to discriminate between the metabolic and microtubule-mediated processes in cell morphogenesis.