Phytochemical basis for multiple borer resistance in maize
1997
Bergvinson, D.J. | Arnason, J.T. | Mihm, J.A. | Jewell, D.C.
One of the major research emphasis's of the CIMMYT maize improvement program has been the development of germplasm with resistance to multiple generations and species of insects as well as resistance to disease pests. During the past decade, CIMMYT entomologists and breeders in collaboration with Cornell University have developed multiple borer resistant (MBR) populations for the major leaf feeding and stalk-boring pests of maize in temperate, subtropical and tropical areas. Identifying the phytochemical mechanisms of resistance employed by MBR genotypes would serve entomologists, breeders and biotechnologists in identifying new sources of resistance and locating major resistant genes within the genome. For MBR genotypes, the resistance mechanism appears to be nutritional in nature. Leaf tissue of MBR genotypes is tough, which may restrict feeding by early instar larvae. MBR genotypes also tend to have reduced nutritional value (lower nitrogen content), and elevated levels of fiber and cell wall phenolics which may account for the elevated leaf toughness. Cell wall phenolics can cross-link the hemicellulose of the cell wall by the action of peroxidase to produce diferulic acid. Approximntaly 80 Per cent of the variation infield leaf ratings for Ostrinia nubilalis could be accounted for by protein, fiber and diferulic acid content in leaf tissue at the mid-whorl stage in plant development.
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