Inheritance of Resistance to Russian Aphid in Wheat

CI2401 is one of the resistant lines to biotype II of Russian wheat aphid (new blotype) recently identified from a wheat introduction. A F2 segregating family derived from CI2401 and Glupro (a susceptible wheat cultivar) was developed to study this resistance gene. F2 seedlings were infested with RWA biotype II of the aphid. Seedlings, reaction was scored as resistant (flat leaves) and susceptible (rolled leaves) 15 and 20 days after inoculation. Segregation of resistance in the population agreed with simple Mendelian ratios (3:1) using chi-square test, and revealed presence of a single dominant gene controlling the resistance to biotype II of RWA in this selection. Forty two pairs of SSR primers covering all chromosome arms were used to determine the RWA-resistance gene location in the wheat genome. Chi-square test showed no deviation from single locus segregation ratios in this population. The only Xbarc126 and Xgwm121 primers which are 7D specific markers were mostly linked markers to the resistance gene and the other markers showed no linkage. This reveals that the resistant gene is located on the 7th chromosome of D genome in wheat like many other previously identified RWA-resistance genes and can be used to develop new RWA-resistant wheat cultivars.