INHERITANCE OF RESISTANCE TO RUSSIAN WHEAT APHID (Diuraphis noxia Kurdjumov) IN BREAD WHEAT (Triticum aestivum L.)

Diuraphis noxia (Kurdjumov) (Hemiptera; Aphididae), Russian wheat aphid (RWA) causes death at heavily infested bread wheat (Triticum aestivum L.) plants. The pest is living in rolling leaves so its chemical control is difficult. The most effective and economical means of controlling Russian wheat aphid is through the use of resistant cultivars. Two resistant lines, 15 (FL302//BUC/PVN/3/RSK/CA8055//CHAM6) and 27 (BIN C 79/F96PYN3-1828) were crossed with susceptible cultivar Basribey in 2010 and the F-1 plants were selfed to produce the F-2 progeny to determine the inheritance mode after exposing to pest in 2011. Chi-square test showed that the segregation ratio fits a one gene segregation ratio of 3:1 resistant:susceptible phenotyping segregation ratio at the P <= 0.75-0.50 and P <= 0.50-0.25 level of probability in combinations respectively. In both combinations, chi-square test results indicated that a single dominant gene with minor genes governed resistance to RWA. Differential set from USDA (United State Department of Agriculture) with different Dn resistance genes used to find out the single dominant gene carrying the resistance. Variance analyses showed that the differences between reactions of resistant genes were important for chlorosis and leaf rolling. The lines carried Dn7 resistant gene exhibited high level of resistance to the pest while moderate resistance conferred by the plants containing Dn6 gene. Reactions of other Dn genes were close to susceptible control cultivars.