PHYSICAL AND BIOCHEMICAL INTERRELATIONSHIPS AMONG WHEAT CULTIVARS ABE, MONON, AND KNOX 62 FOR RESISTANCE TO HESSIAN FLY BIOTYPES B, C, AND D
Abstract
Studies showed that the resistances of wheat cultivars, Abe to biotype C, Monon to biotype C, and Knox 62 to biotype B were stable at a high temperature of 25 C for all larval densities tested. At 25 C almost 100% of Abe seedlings were infested by biotype B, whereas only about 50% of Abe seedling were infested by biotype D. Secondary plant compounds which may occur in wheat were tested topically for toxicity to Hessian fly red larvae of biotypes B and C. The only 2 compounds that caused detrimental effects to both biotypes were vanillin (a phenolic compound) and methoxy-parabenzoate (a fungicide). Both had relatively low toxicity. Wheat stem agglutinin (WSA) found in stem is a protein with apparent high molecular weight. This agglutinin is distinct from wheat germ agglutinin (WGA), for its ability to agglutinate mammalian erythrocytes was not blocked by N-acetylglucosamine and its high molecular weight appeared to be much higher. Topical applications of wheat stem extracts containing the agglutinin from Abe, Monon, and Knox 62 cultivars on first instar Hessian fly larvae were not toxic to both virulent and avirulent larvae. This suggested the necessity of developing a sensitive feeding bioassay in order to evaluate the roles of wheat chemicals in plant-Hessian fly interactions. A candidate biochemical model of the gene-for-gene interrelationship for Abe, Monon, and Knox 62 cultivar vs Hessian fly biotype B, C and D was developed which suggests the possibility that a biochemical recognition between Abe cultivar to biotype B, C, and D is sensitive to an elevated temperature of 25 C. The model also shows the possibility that the resistances of Abe cultivar to biotype C and Monon cultivar to biotype C may possess the same biochemical mechanism of resistance since both have the same biochemical recognition.
Degree
Ph.D.
Subject Area
Plant pathology
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