Limitation of Gaeumannomyces Graminis by Wheat Root Responses to Phialophora Radicicola

SUMMARY Changes in wheat roots invaded by Phialophora radicicola var. graminicola, P. radicicola var. radicicola and Gaeumannomyces graminis var. tritici were explored. Progress of Phialophora radicicola var. graminicola was arrested by lignitubers in the third cortical layer whereas P. radicicola var. radicicola progressed as far as the innermost layer of the cortex, failing to penetrate the endodermis, but was not arrested by detectable structural changes. Both varieties of P. radicicola elicited considerable lignification of the stelar components, and lignification and suberization of the inner tangential wall of the endodermis. When the two species of fungi were inoculated on the same root, P. radicicola var. graminicola prevented Gaeumannomyces graminis var. tritici from spreading longitudinally in the stele.