Detection of effects of nuclear genes on susceptibility to Helminthosporium maydis race T by a root cap cell bioassay for HMT-toxin

Previous attempts to detect effects of nuclear genes on susceptibility of corn to Helminthosporium maydis, race T, with several bioassays for the pathotoxin produced by this pathogen (HMT-toxin) have yielded conflicting results. Ten Texas male sterile corn lines, differing in susceptibility to H. maydis race T, were tested for sensitivity to HMT-toxin using a recently developed bioassay based on lethal effects on isolated root-cap cells. Susceptibility to H. maydis, race T, was found to be generally correlated with sensitivity to HMT-toxin. Preliminary results with two other phytotoxins suggest that this root cap cell bioassay should provide a rapid, accurate and economical method of testing agricultural chemicals or other agents for phytotoxicity.