Genetics of stripe rust resistance in two barley (Hordeum vulgare L.) genotypes

Abstract

Stripe rust inflicted by the pathogen Puccinia striiformis Westend. f. sp. hordei Eriks can cause marked grain yield reduction and deterioration of the malting quality in barley. Two barley genotypes, DWRB137 (DWR28/DWRUB64) and DWRB143 (DWRB73/DWR83) were identified as resistant (R) for three stripe rust races viz., 57 (0S0), M (1S0) and Q (5S0) at seedling and adult plant stages. These genotypes were crossed with two stripe rust susceptible (S) barley cultivars, RD2035 and Lakhan to study mode of inheritance of stripe rust resistance. All the F1 plants showed resistance against stripe rust race, 57 (0S0) indicating that the resistance (R) is dominant. The F2 generations derived from the crosses namely, Lakhan/DWRB137, Lakhan/DWRB143, RD2035/DWRB137 and RD2035/DWRB143 were tested with inoculum of race, 57 (0S0) under artificially inoculated conditions. The observed frequency of segregants in each F2 generation fit well in a theoretical ratio of 3(R):1(S) (χ 2(T) less than 0.01) indicating that the resistance against the tested race is controlled by a single dominant gene in the genotypes, DWRB137 and DWRB143. To validate the F2 hypothesis, the F3 progenies were also tested under above described conditions and followed discrete segregation of 1 (R): 2 (Segregating): 1(S) ratio in all the four crosses. Test of allelism was also conducted to establish the identity of resistance gene(s) present in the resistant genotypes. The F2 population derived from DWRB137/DWRB143 (R × R) cross fit to 15(R):1(S) ratio showing that the two genotypes had different resistance genes.