Network analysis reveals the root endophytic fungi associated with Fusarium root rot invasion

Abstract

Root rot caused by Fusarium sp., a ubiquitous soilborne disease, leads to huge economic losses for tobacco cultivation in China. However, comprehensive knowledge about the interactions between this fungal pathogen and other members of soil and endophytic fungal communities is very limited. In this study, how the invasion process of root rot disease affect the fungal communities of soils and endophytes was systematically studied by using both internal transcribed spacer (ITS) sequencing and molecular ecological network analysis (MENA). The root endophytic fungal community diversity of root rot was 23.99 % and 76.27 % higher than healthy roots according to Shannon and Inv-Simpson indices, respectively. By integrating both community composition analysis and field disease symptoms, the root rot pathogen of this study was identified as Fusarium oxysporum f. sp. psidii. Soil and endophytic fungal communities affected by this pathogen showed more complex network structures and greater number of interaction relationships than those of healthy plants. Besides, the pathogen F. oxysporum had successfully invaded the roots and become a keystone species of endophytic fungal community during the invasion process. In addition, the genera Haematonectria and Ceratobasidium were positively correlated with the pathogen while the genera Eupenicillium, Alternaria, and two unclassified fungi were negatively correlated with the pathogen in the networks of infected roots. These fungi may play important roles in assisting and resisting root rot pathogen invasion, respectively.