Identification of wheat chromosomes involved with different types of resistance against greenbug (Schizaphis graminum, Rond.) and the Russian wheat aphid (Diuraphis noxia, Mordvilko)

Two sets of intervarietal chromosome substitution lines in the recipient, s usceptible cultivar 'Chinese Spring' were screened to identify the wheat ch romosomes involved with antixenosis, antibiosis and tolerance resistance to greenbug and Russian wheat aphid. The amphiploid 'Synthetic' and the culti var 'Hope' were the donor parents. Antixenosis, antibiosis and tolerance we re evaluated with conventional tests in controlled environmental conditions using a clone of greenbug biotype C and a clone of RWA collected on wheat. Antixenosis against greenbug was accounted for by several chromosomes in b oth sets of substitution lines with chromosome 2B contributing the highest level of this type of resistance. The highest levels of antixenosis against RWA were associated with the group of chromosomes 7 of the substitutions C S/Syn set and the chromosome substitutions 2B, 6A and 7D of the CS/Hope set . Antibiosis against both aphids species was accounted for by several diffe rent chromosomes. The highest levels of antibiosis for most of RWA resistan ce traits were recorded from the 1B substitution line of the CS/Hope set. M ore than one gene appears to determine antibiosis. Tolerance to both greenb ug and the RWA was significantly associated with chromosomes 1A, 1D, and 6D in the CS/Syn set of substitutions. These lines showed enhanced plant grow th under aphid infestation. The highest levels of antixenosis, antibiosis a nd tolerance against the two aphid species occurred mostly in different sub stitution lines. Consequently, the different types of resistance for both p ests seem to be partially independent. Since different genes seem to be inv olved in at least several traits of the resistance categories against the t wo aphid species, such genes could be combined in new cultivars of wheat to broaden their genetic base of resistance against the greenbug and the RWA.