AUTHOR=Yuan Qing-Song , Wang Lu , Wang Hui , Wang Xiaoai , Jiang Weike , Ou Xiaohong , Xiao Chenghong , Gao Yanping , Xu Jiao , Yang Ye , Cui Xiuming , Guo Lanping , Huang Luqi , Zhou Tao 

TITLE=Pathogen-Mediated Assembly of Plant-Beneficial Bacteria to Alleviate Fusarium Wilt in Pseudostellaria heterophylla

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.842372

DOI=10.3389/fmicb.2022.842372

ISSN=1664-302X

ABSTRACT=<p><italic>Fusarium</italic> wilt (FW) is a primary replant disease that affects <italic>Pseudostellaria heterophylla</italic> (Taizishen) and is caused by <italic>Fusarium oxysporum</italic>, which occurs widely in China under the continuous monocropping regime. However, the ternary interactions among the soil microbiota, <italic>P. heterophylla</italic>, and <italic>F. oxysporum</italic> remain unknown. We investigated the potential interaction relationship by which the pathogen-mediated <italic>P. heterophylla</italic> regulates the soil and the tuberous root microbiota <italic>via</italic> high-throughput sequencing. Plant–pathogen interaction assays were conducted to measure the arrival of <italic>F. oxysporum</italic> and <italic>Pseudomonas poae</italic> at the tuberous root <italic>via</italic> qPCR and subsequent seedling disease incidence. A growth assay was used to determine the effect of the tuberous root crude exudate inoculated with the pathogen on <italic>P. poae</italic>. We observed that pathogen-mediated <italic>P. heterophylla</italic> altered the diversity and the composition of the microbial communities in its rhizosphere soil and tuberous root. Beneficial microbe <italic>P. poae</italic> and pathogen <italic>F. oxysporum</italic> were significantly enriched in rhizosphere soil and within the tuberous root in the FW group with high severity. Correlation analysis showed that, accompanied with FW incidence, <italic>P. poae</italic> co-occurred with <italic>F. oxysporum</italic>. The aqueous extract of <italic>P. heterophylla</italic> tuberous root infected by <italic>F. oxysporum</italic> substantially promoted the growth of <italic>P. poae</italic> isolates (H1-3-A7, H2-3-B7, H4-3-C1, and N3-3-C4). These results indicated that the extracts from the tuberous root of <italic>P. heterophylla</italic> inoculated with <italic>F. oxysporum</italic> might attract <italic>P. poae</italic> and promote its growth. Furthermore, the colonization assay found that the gene copies of <italic>sucD</italic> in the <italic>P. poae</italic> and <italic>F. oxysporum</italic> treatment (up to 6.57 × 10<sup>10</sup>) group was significantly higher than those in the <italic>P. poae</italic> treatment group (3.29 × 10<sup>10</sup>), and a pathogen-induced attraction assay found that the relative copies of <italic>sucD</italic> of <italic>P. poae</italic> in the <italic>F. oxysporum</italic> treatment were significantly higher than in the H<sub>2</sub>O treatment. These results showed that <italic>F. oxysporum</italic> promoted the colonization of <italic>P. poae</italic> on the tuberous root <italic>via F. oxysporum</italic> mediation. In addition, the colonization assay found that the disease severity index in the <italic>P. poae</italic> and <italic>F. oxysporum</italic> treatment group was significantly lower than that in the <italic>F. oxysporum</italic> treatment group, and a pathogen-induced attraction assay found that the disease severity index in the <italic>F. oxysporum</italic> treatment group was significantly higher than that in the H<sub>2</sub>O treatment group. Together, these results suggest that pathogen-mediated <italic>P. heterophylla</italic> promoted and assembled plant-beneficial microbes against plant disease. Therefore, deciphering the beneficial associations between pathogen-mediated <italic>P. heterophylla</italic> and microbes can provide novel insights into the implementation and design of disease management strategies.</p>