Plant Genotype Influences Mycorrhiza Benefits and Susceptibility to a Soil Pathogen

Abstract

Abstract This study examines the role mycorrhizae may play in protecting host plants from a soil fungal pathogen. Asexual propagules of three Allium vineale genotypes were grown in the presence and absence of mycorrhizae and the pathogen, Sclerotium cepivorum (white rot), with some plants encountering the mycorrhizal fungi first and others encountering the pathogen first. A significant three-way interaction indicates plant genotypes vary in response to the combined effects of mycorrhizae and the pathogen, with the A. vineale genotype most resistant to the pathogen deriving the least growth benefit from mycorrhizae and the genotype most susceptible to the pathogen receiving the highest relative growth benefit from mycorrhizae, despite there being no difference in the level of mycorrhizal colonization among the plant genotypes. No evidence was found that the presence of mycorrhizae reduced the impact of the pathogen for the most susceptible plant genotype (B). These findings support the hypothesis the prima...