INHERITANCE OF CYCLIC HYDROXAMATES IN Zea mays L.

Abstract

Hydroxamic acids have been implicated in the resistance of corn (Zea mays L.) to both fungi and insects. In this study, five selected crosses were used among the four inbreds BxBx, bxbx, B49 and B37 to study inheritance of hydroxamates. Hydroxamate concentration in the parental, F1, F2 and backcross generations for each cross was estimated by a rapid procedure based upon the colorimetric reaction of hydroxamates with FeCl3. Components of variance and estimates of heritability were obtained by the procedures of Warner (1952). F2 and backcross data indicated that concentration of hydroxamates is controlled monogenically in the cross bxbx × BxBx and polygenically in the crosses bxbx × B49 and bxbx × B37. Estimates of gene number using the Castle-Wright formula indicated that hydroxamate concentration is conditioned in B49 and B37 by five and two loci, respectively. The addition of BxBx to either B49 or B37 increased the frequency of genotypes in F2 with a high concentration of hydroxamates. Additive genetic variance was the most important component of the phenotypic variance and resulted in estimates of heritability from 0.64 to 0.79. However, the dominance component of variance was considerably higher for crosses involving BxBx than for the crosses bxbx × B49 and bxbx × B37.

Crop cultivars with allelopathic capability

“…General combining ability accounted for 91% of the variation among hybrids in DIMBOA concentration. From the F 2 and backcross data in maize, Dunn et al . (1981 ) found that the production of hydroxamate is controlled monogenetically in the cross bxbx × BxBxm, and polygenetically in the crosses bxbx × B49 and bxbx × B37.…”

Genetics of Secondary Metabolism and Herbivore Resistance in Plants

“…Likely candidate compounds included the hydroxamic acids (e.g., 2,4-dihydroxy-7-methoxy-2H-l,4-benzoxazin-3(4H)-one, DIMBOA) and their benzoxazolinone derivatives. In at least one line of corn, hydroxamic acid concentrations are determined by a single major partially dominant gene Bx; in other inbred lines, however, hydroxamic acid concentrations are inherited quantitatively, with from two to five loci involved (Dunn et al, 1981). Depending on the variety, hydroxamic acid levels can be influenced by environmental conditions, including light intensity, temperature, and iron and nitrogen concentrations (Nie meyer, 1988).…”

“…According to Ehrlich and Raven (1964), plant chemistry acts as a major selective agent on insect populations. More than 25 years later, there is little evidence that chemistry per se is accountable for genetically based differences in insect performance on different host plants (and no evi dence of which we are aware that chemistry is accountable for genetically based differences in performance of any other type of herbivore).…”

“…More than 25 years ago, Ehrlich and Raven (1964) postulated that "the evolution of secondary plant substances and the stepwise evolutionary responses to these by phytophagous insects have clearly been the dom inant factors in the evolution of butterflies and other phytophagous groups (p. 602)."…”