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Résumé :
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Interaction between the Russian wheat aphid, Diuraphis noxia (Mordvilko), and the resistant wheat, Triticum aestivum L., plant introduction lines PI 137739, PI 140207, and PI 262660 and the susceptible wheat cultivar 'Stephens' were studied. D. noxia reproductive rate and population development were higher when fed on Stephens compared with the resistant genotypes. Reproductive rate of D. noxia decreased as aphid density and length of aphid time on plant increased. Whereas, D, noxia populations increased with increasing aphid densities and length of aphid time on plant. Although the populations of D. noxia were lower when fed resistant genotypes, total chlorophyll content was reduced compared with the susceptible genotype. This could have been caused by increased aphid probing activity on resistant genotypes. There was no significant difference between the antibiotic line PI 140207 and the tolerant line PI 262660 in aphid reproductive rate, population density or reduction in leaf chlorophyll content. Expression of several polypeptides were altered by D. noxia feeding on PI 137739 and Stephens. Three polypeptides of sizes approximate to 32, 33, and 35 k were enhanced in PI 137739 but not in Stephens. Involvement of these proteins in plant defense is discussed.
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