Inducing disease resistant maize mutations via ionizing radiation

The smut (Ustilago Zeae), maize mosaic dwarf virus and helminthosporium turcicum resistance of maize mutant lines (M5-M6) was studied. The initial material (seeds of inbred lines and hybrids) was irradiated by γ-rays and fast neutrons. The lines were sown on an infected field and artificially inoculated for a period of three years. Smut inoculation was effected by injecting a spore suspension, mosaic virus - by use of leaf aphids and helminthosporium - by placing infection material consisting of finely ground diseased leaves in the plant's leaf spirale. Smut and mosaic infections were scored in percent of diseased plants vs. healthy ones, while Helminthosporium resistance was evaluated visually after Sheludko's (1961) scale. Several disease resistant induced mutant lines have been selected, namely: Pr-169, which has a high resistance to maize smut, Ph-249 - helmintosporium resistant, and Wh-661 and Wh-669 - resistant both to helminthosporium and to mosaic virus. (author)