Associated bacteria of different life stages of Meloidogyne incognita using pyrosequencing‐based analysis

Abstract

The root knot nematode (RKN), Meloidogyne incognita, belongs to the most damaging plant pathogens worldwide, and is able to infect almost all cultivated plants, like tomato. Recent research supports the hypothesis that bacteria often associated with plant-parasitic nematodes, function as nematode parasites, symbionts, or commensal organisms etc. In this study, we explored the bacterial consortia associated with M. incognita at different developmental stages, including egg mass, adult female and second-stage juvenile using the pyrosequencing approach. The results showed that Proteobacteria, with a proportion of 71-84%, is the most abundant phylum associated with M. incognita in infected tomato roots, followed by Actinobacteria, Bacteroidetes, Firmicutes etc. Egg mass, female and second-stage juvenile of M. incognita harbored a core microbiome with minor difference in communities and diversities. Several bacteria genera identified in M. incognita are recognized cellulosic microorganisms, pathogenic bacteria, nitrogen-fixing bacteria and antagonists to M. incognita. Some genera previously identified in other plant-parasitic nematodes were also found in tomato RKNs. The potential biological control microorganisms, including the known bacterial pathogens and nematode antagonists, such as Actinomycetes and Pseudomonas, showed the largest diversity and proportion in egg mass, and dramatically decreased in second-stage juvenile and female of M. incognita. This is the first comprehensive report of bacterial flora associated with the RKN identified by pyrosequencing-based analysis. The results provide valuable information for understanding nematode-microbiota interactions and may be helpful in the development of novel nematode-control strategies.

The bacterial community of entomophilic nematodes and host beetles

“…and Pedobacter sp. (Baquiran et al 2013), while the associated bacteria of the plant parasitic nematode Meloidogyne incognita are mostly Proteobacteria (Cao et al 2015). Furthermore, our data do not support the hypothesis that the entomophilic nematodes play a role in transmitting the species-specific beetle bacteria because the bacterial taxa do not drive differences between the nematodes' bacterial microbiome, that is the bacteria found with different nematodes do not exhibit signatures specific either to nematodes or their host beetles.…”

“…), while the associated bacteria of the plant parasitic nematode Meloidogyne incognita are mostly Proteobacteria (Cao et al . ).…”

Microbiomes associated with infective stages of root-knot and lesion nematodes in soil

“…penetrans all life stages are infective. This could influence our results as the surfaces of life stages differ [40] and might attract different microbial species [43, 44]. …”

“…In our study we aimed to completely remove loosely attached microbes from the nematodes by several washing steps. In contrast, Cao et al [43] analyzed the bacteria associated with J2 of M . incognita without such effort and found a diversity of bacterial genera which much resembled what is typically found in soil.…”

Comparative Metagenomic Analysis of Rhizosphere Microbial Community Composition and Functional Potentials under Rehmannia glutinosa Consecutive Monoculture

“…Many previous findings have demonstrated the concomitant occurrence of Sphingomonadaceae and Streptomycetaceae in the rhizosphere under consecutive monoculture or upon fungal pathogen invasion [32,33]. Members of Streptomycetaceae and Sphingomonadaceae living in soil could decompose dead plants and fungi by synthesizing cellulose-, pectin-, xylan-, and chitin-degrading enzymes [32,34,35]. Therefore, the increase of Sphingomonadaceae and Streptomycetaceae in rhizosphere might be important indicator microorganisms of root damage by soil fungal pathogens [32], but more direct and comprehensive studies are required to test this hypothesis in R. glutinosa monoculture regime.…”