EFFECTS OF ALIEN AND INTRASPECIES CYTOPLA SMS ON MANIFESTATION OF NUCLEAR GENES FOR WHEAT RESISTANCE TO BROWN RUST .2. SPECIFICITY OF CYTOPLASM INFLUENCE ON DIFFERENT LR GENES

Specificity of expression of the major nuclear genes Lr to two brown r ust clones in hybrids with the same maternal cytoplasm was analyzed. I t was evaluated by a resistant : susceptible ratio in the F-2. Recipro cal hybrids were obtained from the cross between the progeny of homozy gous susceptible plants of the cultivar Penjamo 62 and its alloplasmat ic lines carrying cytoplasms of Triticum dicoccoides var. fulvovillosu m, Aegilops squarrosa var. typica, Agropyron trichophorum, and isogeni c lines of the cultivar Thatcher (Th) with the Lr1, Lr9, Lr15, and Lr1 9 genes. It was shown that the effect of the Lr1 gene in the cytoplasm of cultivar Thatcher and in eu-, and alloplasmatic forms of Penjamo 6 2 was less expressed than that of other Lr genes. Cytoplasm of the all oplasmatic line (dicoccoides)-Penjamo 62 was the only exception: in th e Fz, hybrids with Th (Lr1) had a higher yield of resistant forms than those with Th (Lr15). In the hybrid combinations studied, expression and/or transmission of the Lr19 gene was more significant than that of other genes. This gene had no advantages over Lr15 and Lr19 only in c ytoplasm of the alloplasmatic line (squarrosa)-Penjamo 62. In certain hybrid cytoplasms, the display of the Lr1, Lr15, and Lr19 genes, in co ntrast to Lr9, varied with the virulence of the pathogen clones.