Partial resistance to Puccinia triticina in certain Triticum species

Abstract

Resistance to rust diseases of common wheat (Triticum aestivum) has often been transferred from related species. These alien genes usually mediate hypersensitive, and frequently non-durable, resistance to leaf rust caused by Puccinia triticina. Partial resistance may be more durable than hypersensitive resistance and is expressed by a susceptible host reaction but slower rate of disease development. The aim of this study was to quantify components of resistance to leaf rust in certain Triticum species. Accessions selected were previously shown to produce smaller or fewer leaf rust pustules without the characteristic chlorosis and necrosis associated with hypersensitive resistance. Latent period of leaf rust, uredium size and density, and infection type were determined in two experiments on flag leaves of 13 accessions of Triticum turgidum, T. timopheevii and T. tauschii. Plants were quantitatively inoculated with pathotype UVPrt13. Accessions of T. timopheevii and T. turgidum, showed high levels of partial resistance with an increase in latent period, reduced uredia per cm² and reduced uredium size. Transfer of such resistance to commercial wheat varieties should contribute to long-lasting genetic control of leaf rust.