GENETICS OF ADULT-PLANT LEAF RUST RESISTANCE IN CHINESE SPRING AND STURDY WHEATS

The common wheat (Triticum aestivum L.) cultivars Chinese Spring and Sturdy have adult-plant resistance to leaf rust caused by Puccinia recondita Rob. ex Desm. To study the genetics of this resistance both cultivars were crossed and backcrossed to 'Thatcher', a leaf rust susceptible cultivar. The two cultivars or resistant selections from the above crosses were also crossed with backcross lines having Lr12, Lr13, and Lr34 genes for adult-plant leaf rust resistance. The backcross F2 families and F2 populations were grown in a field rust nursery artificially inoculated with a mixture of P. recondita isolates. The segregation for rust reaction of adult plants indicated that both cultivars have a combination of genes Lr12 and Lr34. To assist in the identification of Lr34 in these cultivars, adult-plant leaf rust resistance from each cultivar was transferred into Thatcher.