Microscopic study of the development of yellow rust ( Puccinia striiformis) in a wheat cultivar showing adult plant resistance

Abstract

The development of yellow rust in leaves of a wheat cultivar, showing seedling susceptibility and adult plant resistance was examined using light and electron microscopy. Resistance during the early stages of disease development (2 to 6 days after inoculation) appeared to be associated with a specific inhibition of fungal colony growth and haustorium formation but there was little effect on the microscopic or ultrastructural appearance of either the host or the pathogen. During the latter part of the disease cycle (6 to 16 days after inoculation) resistance was associated with changes in the physiology of the host cells leading to cellular disruption, a response which may have restricted the supply of host metabolites to the fungus and possibly released toxic factors.