Several dek mutants in our collection have not been uncovered by any of the B-A translocations tested. These mutants may lie between the breakpoints for those chromosomes with B-A translocations on both sides of the centromere, or on an arm not uncovered by a B-A translocation. Chromosome 8 is of the latter type. In order to locate mutants potentially on the short arm of chromosome 8, 17 previously unlocated dek mutants were tested this past summer. All of these mutants had been adequately tested by the full B-A set, including TB-8Lc, and were not located. For each mutant, 100-seed samples from 3 normal ears crossed by TB-8Lc were planted. Based on morphology and pollen sterility, 15-20 plants in each family were classified as hypoploids. Compared to normal sibs, the hypoploids were short plants with dark green, glossy, broad crinkled leaves. Part of the leaf tissue was burned by sunshine, indicating a sensitivity to heat or light. These plants had more internodes and shorter internode length. Tassels came out one week later and pollen shed was good. Anthers were smaller in size. The table lists the plant height, 5th leaf length and width, and internode length for normal and hypoploid plants. Data were collected from five plants of each type at random. Good selfs segregating for mutant kernels were obtained from hypoploids of each of the 17 mutants. Fourteen of the 17 mutant ears had 3:1 segregating ratio, and 3 gave ears with a majority of mutant kernels, indicating that the mutant was probably located proximal to the 8Lc breakpoint, and possibly in the short arm of chromosome 8. These three mutants (E1089, E1092, E1168) will be incorporated into 3 point linkage analysis of chromosome 8.
M-T. Chang and M. G. Neuffer
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