First touch: An immediate response to surface recognition in conidia of Blumeria graminis

Conidia of the plant pathogen Blumeria graminis recognize and respond to features of certain substrata. Appropriate surfaces induce release of an extracellular proteinaceous matrix from the body of the conidium. Contact with a hydrophobic substratum elicits almost immediate release of the matrix at the contact interface. In this investigation we present, for the first time, evidence that recognition of the substratum by conidia can stimulate uptake of anionic, low-molecular-weight materials before germination. This facilitated transport could be a mechanism for recognition of the host and determination of the direction of growth of the emerging germ tube toward the host leaf surface

Resistance responses of albino leaves of Triticum timopheevii mutants inoculated with Erysiphe graminis f.sp. tritici

Albino chlorophyll mutants induced in Triticum timopheevii by gamma-irradiation were used to study the influence of photosynthetic activity on the development of two isolates of Erysiphe graminis f.sp. tritici. and host resistance responses, 72 h after inoculation. The results showed that the percentage of pathogenic units inhibited by papilla response and epidermal cell hypersensitivity was lower on albino primary seedling leaves than on normal green seedling leaves. On albino leaves, the development of pathogenic units which established a successful penetration was either decreased or retarded, depending on the isolate used. This effect could be attributed to the limited supply of assimilates from the albino host due to the lack of photosynthetic activity