INHERITANCE OF ADULT-PLANT LEAF RUST RESISTANCE DERIVED FROM THE COMMON WHEAT VARIETIES EXCHANGE AND FRONTANA

Abstract

Introdllction Resistance of wheat to leaf rust, caused by Pucci~zin reco7zclitn Rob. ex Desm. f. sp. tritici, may be expressed at the first-leaf stage (seedling resistancc) or only at some subsequent stage of plant development (adult-plant resistance). Seedling-plant reactions are used for the identification of rust races, and thc genetic behaviour of many genes for seedling resistance has becn thoroughly investigated. In contrast, the nature of adult-plant resistance is poorly understood. I t is also not known how genes for adult-plant resistance and the corresponding genes for virulence and avirulence in thc pathooen fit current 4 concepts of host-parasite interactions. Investigations into thc inheritance of this forill of resistancc have not been too successful but suggest a morc con~plcx situation than is common with genes conditioning secdling resistancc. In this investigation the inheritance of adult-plant resistance was studied in the common \\,heat varieties Exchange and Frontana, and varicties that havc rcsistancc transferred from these varietics by bacltcrossing. Exchangc and Frontana arc highly resistant to leaf rust under field conditions in Canada.