Eight Loci for Resistance to Ustilago tritici Race T11 Indicated in 20 Wheat Lines

Loose smut of wheat is a disease of world wide significance. Resistant cultivars constitute a potentially useful and environmentally benign method of controlling this disease. The genetic basis of resistance in 20 wheat genotypes with resistance to Ustilago tritici race T11 was studied in crosses with the widely grown but susceptible Indian cultivar, PBW 343. These lines were also involved in 10 'resistant x resistant' crosses, to infer diversity for resistance genes in this set. All 30 crosses were developed to the F(3) stage. Fifteen parents were inferred to carry dominant genes for resistance to race T11. Ten of these resistant lines (ML 521, W 59, W 1616, W 2484, W 2531, W 5915, W 6202, WL 1786, WL 2956 and WL 3450) had resistance controlled by 2 dominant genes acting in a complementary manner whereas in 4 lines (W 4461, W 5100, W 2615 and WL 3951), there was a single dominant gene and in a single genotype, WL 5907, there were 2 dominant genes with duplicate gene action governing the resistance. In lines W 2139, W 3899, W 4985, W 5450 and W 5792 a single recessive gene conferred resistance. Inheritance in two crosses, one derived from a line possessing a single dominant gene and the other from a line possessing a single recessive gene was re-analyzed and successfully confirmed in F(5) generation. The segregation of most of the 'resistant x resistant' crosses conformed to the inferences drawn about the parents in the 'resistant x susceptible' crosses.