Response of endophytic bacterial communities in banana tissue culture plantlets to Fusarium wilt pathogen infection

Abstract

Endophytic bacteria reside within plant hosts without having pathogenic effects, and various endophytes have been found to functionally benefit plant disease suppressive ability. In this study, the influence of banana plant stress on the endophytic bacterial communities, which was achieved by infection with the wilt pathogen Fusarium oxysporum f. sp. cubense, was examined by cultivation-independent denaturing gradient gel electrophoresis analysis of 16S ribosomal DNA directly amplified from plant tissue DNA. Community analysis clearly demonstrated increased bacterial diversity in pathogen-infected plantlets compared to that in control plantlets. By sequencing, bands most similar to species of Bacillus and Pseudomonas showed high density in the pathogen-treated pattern. In vitro screening of the isolates for antagonistic activity against Fusarium wilt pathogen acquired three strains of endophytic bacteria which were found to match those species that obviously increased in the pathogen infection process; moreover, the most inhibitive strain could also interiorly colonize plantlets and perform antagonism. The evidence obtained from this work showed that antagonistic endophytic bacteria could be induced by the appearance of a host fungal pathogen and further be an ideal biological control agent to use in banana Fusarium wilt disease protection.

Endophytic bacteria from banana cultivars and their antifungal activity

“…The ratio of the number of isolates with antagonistic activity to the total number of isolated bacteria (4/122) was relatively lower than that found by Wang et al (2012), who obtained 6 antagonistic bacteria of 57 bacterial strains that were isolated from the rhizospheres of healthy banana plants that were grown in a heavily wilted and diseased field. A greater number of endophytes with antagonistic activity have been observed in plants subjected to biotic stress (Lian et al, 2008).…”

“…In banana plants, an analysis of the response of endophytic bacterial communities in plantlets derived from tissue cultures infected with a Fusarium oxysporum f. sp cubense (FOC) race 4 pathogen showed that antagonist endophytic bacterial communities tended to increase in FOC-inoculated banana plants, indicating that the presence of the pathogen played a role in the selection of antagonists (Lian et al, 2008). Endophytic bacteria isolated from older banana leaves exhibited higher percentages of antagonistic activity against Mycosphaerella fijiensis, which affected the morphology of the mycelia and ascospores (Ceballos et al, 2012).…”

Analysis of the Bacterial Diversity Associated with the Roots of Maize (Zea mays L.) through Culture-Dependent and Culture-Independent Methods

“…In agreement with these previous surveys, within the Firmicutes group we identified Bacillus species from both the rhizoplane and root inner tissues of maize seedlings and Enterobacter and Pseudomonas were found as main genera within the γ-Proteobacteria. Bacteria from Bacillus genus have been reported as maize kernel endophytes [10] and have been isolated not only from maize [10,18,26] but also from many different plants such as peas, potatoes, conifers, bananas, and bean [27][28][29][30][31]. Their activities as biocontrol agents of various fungi [32,33], as phosphorous solubilizers [34] and as auxin producers [35] have also been reported.…”

Biocontrol of Fusarium wilt of banana: Key influence factors and strategies

“…These effects exert strong negative influences on the colonization of the heterologous antagonistic microbes in banana plants. To overcome these difficulties, a proposal is to screen active antagonistic microbes from the endophytic strains of healthy banana plants (Lian et al, 2008). The use of endophytes as antagonist is of great interest because of their ability to colonize plant tissue and produce antibiotics in situ (Sessitsch et al, 2004).…”