Mefluidide {N-[2,4-dimethyl-5-[[(trifluoromethyl) sulfonyl] amino] phenyl] acetamide} was evaluated for effects on corn [Zea mays(L.) ‘Pioneer 3535’] coleoptile elongation. Mefluidide at 10-8M, 10-7M, and 10-6M stimulated elongation approximately equal to growth stimulations with 10-6M indoleacetic acid (IAA). Polar transport of14C-IAA from donor agar blocks through corn coleoptiles and into receiver agar blocks after 12 h was increased 246% by 10-4M mefluidide and inhibited 82% by 10-3M mefluidide. Mefluidide-related chemicals (10-4M) lacking a trifluoromethyl-sulfonyl-amino chain at the 1-position of the phenyl ring did not alter14C-IAA transport. IAA transport was increased 97% when the acetamide chain at the 5-position was absent and 255% when the methyl in the 4-position was absent, and it decreased 65% when the methyl at the 2-position was absent. Polar transport of14C-IAA through soybean [Glycine max(L.) Merr. ‘Williams’] hypocotyls was not altered by 10-4M mefluidide; however, 10-3M mefluidide increased IAA transport 116%. After 6 h, corn coleoptiles metabolized 14% of the mefluidide absorbed and soybean metabolized 54% of the mefluidide absorbed from14C-mefluidide solutions (10-6M). Differences in the rate of metabolism of mefluidide in meristematic tissue of corn and soybean may explain differences in mefluidide effects on auxin transport in corn and soybean.
Wounding Response in Relation to Polar Transport of Radiocalcium in Isolated Root Segments of Zea mays