The ubiquity of non‐specific eliciting activity in intercellular washing fluids from rust‐infected wheat leaves

Abstract

Intercellular washing fluids (IWF) were harvested from a range of wheat cultivars infected with either the leaf rust fungus (Puccinia recondite f.sp. tritici) or the stem rust fungus (Puccinia graminis f.sp. tritici). These fluids were then tested for their ability to elicit symptoms of chlorosis and necrosis in 14 wheat cultivars. Eliciting activity was found in all samples tested, irrespective of both the host cultivar infected by the rust fungus and the genotype of the infecting pathogen isolate. Healthy test cultivars either responded to all IWF preparations or were responsive to none of them. Investigations into the nature of this non‐specific eliciting activity revealed that active molecules are periodate sensitive, negatively charged at neutral pH, and associated with a high molecular weight fraction.