Degradation of soil arbuscular mycorrhizal fungal diversity and functionality accompanied by the aggravation of pepper Phytophthora blight in a facility shed in Southwest China

Abstract

AbstractArbuscular mycorrhizal (AM) fungi play a vital role in plant's resistance against soil‐borne pathogens including Phytophthora capsici, which causes the devastating Phytophthora blight and threatens pepper (Capsicum annuum L.) cultivation worldwide. In order to understand the interaction of indigenous AM fungal community and P. capsici during the aggravation of Phytophthora blight, a survey was performed in a facility shed in Southwest China. The blight severity of pepper plants was evaluated based on a 0–5 scale (L0–L5), and the corresponding root AM fungal colonization, and the abundance and community composition of AM fungi as well as the population of P. capsici in root‐adjacent soil, were all investigated. Along with the rise of disease severity, increased soil P. capsici population was shown. In contrast, there were significant decreases in root colonization rate and the diversity indices rather than the abundance of soil AM fungi. The root colonization rate and the diversity indices of AM fungi all showed significant negative correlations with soil P. capsici population. Compared to plants with lower disease severities (L0–L2), higher severities (L3–L5) significantly modified soil AM fungal community composition, mainly through replacing the beneficial Glomus phylotypes by Paraglomus ones. Overall, the results disclosed the dynamic competition between indigenous AM fungi and P. capsici behind the onset of pepper Phytophthora blight, which highlights the importance of establishing soil suppressiveness on the control of soil‐borne diseases.