Plant growth-promoting endophytic bacteria versus pathogenic infections: an example of Bacillus amyloliquefaciens RWL-1 and Fusarium oxysporum f. sp. lycopersici in tomato.

Raheem Shahzad,Abdul Latif Khan,Saqib Bilal,In-Jung Lee,Sajjad Asaf

doi:10.7717/peerj.3107

Raheem Shahzad, Abdul Latif Khan + Show 3 more

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https://doi.org/10.7717/peerj.3107

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Journal: PeerJ	Publication Date: Mar 16, 2017
Citations: 89	License type: CC BY 4.0

Affiliation: Kyungpook National University, University of Nizwa

Abstract

Fungal pathogenic attacks are one of the major threats to the growth and productivity of crop plants. Currently, instead of synthetic fungicides, the use of plant growth-promoting bacterial endophytes has been considered intriguingly eco-friendly in nature. Here, we aimed to investigate the in vitro and in vivo antagonistic approach by using seed-borne endophytic Bacillus amyloliquefaciens RWL-1 against pathogenic Fusarium oxysporum f. sp. lycopersici. The results revealed significant suppression of pathogenic fungal growth by Bacillus amyloliquefaciens in vitro. Further to this, we inoculated tomato plants with RWL-1 and F. oxysporum f. sp. lycopersici in the root zone. The results showed that the growth attributes and biomass were significantly enhanced by endophytic-inoculation during disease incidence as compared to F. oxysporum f. sp. lycopersici infected plants. Under pathogenic infection, the RWL-1-applied plants showed increased amino acid metabolism of cell wall related (e.g., aspartic acid, glutamic acid, serine (Ser), and proline (Pro)) as compared to diseased plants. In case of endogenous phytohormones, significantly lower amount of jasmonic acid (JA) and higher amount of salicylic acid (SA) contents was recorded in RWL-1-treated diseased plants. The phytohormones regulation in disease incidences might be correlated with the ability of RWL-1 to produce organic acids (e.g., succinic acid, acetic acid, propionic acid, and citric acid) during the inoculation and infection of tomato plants. The current findings suggest that RWL-1 inoculation promoted and rescued plant growth by modulating defense hormones and regulating amino acids. This suggests that bacterial endophytes could be used for possible control of F. oxysporum f. sp. lycopersici in an eco-friendly way.

Highlights

Plant growth and productivity is strongly affected by the associated microbiota in the soil
Looking at the prospects of endophytic microbial application to crop disease resistance, in the current study, we aimed to evaluate the in vitro and in vivo antifungal capability of Bacillus amyloliquefaciens RWL-1 against F. oxysporum f. sp. lycopersici, and to locate the potential mechanism concerned with the bio-control of F. oxysporum f. sp. lycopersici concerning phytohormonal modulation and amino acid regulation in tomato plants
In vitro antifungal assay The potential of Bacillus amyloliquefaciens RWL-1 to inhibit the growth of F. oxysporum f. sp. lycopersici was assessed using dual culture technique (Fig. 1)

Summary

Introduction

Plant growth and productivity is strongly affected by the associated microbiota in the soil. These microbial resources can influence the fitness and survival of plants, either. How to cite this article Shahzad et al (2017), Plant growth-promoting endophytic bacteria versus pathogenic infections: an example of Bacillus amyloliquefaciens RWL-1 and Fusarium oxysporum f. Soil-borne plant pathogens are hazardous to the plant growth and productivity (Gajbhiye et al, 2010). Fusarium oxysporum is a pervasive soil-borne phytopathogen that can cause serious diseases such as vascular wilt, root rot, and damping off in many plants (McGovern, 2015). Tomato is one of the most important crops sensitive to such infections worldwide, and is especially sensitive to vascular wilt by F. oxysporum (Inami et al, 2014). F. oxysporum percolate inside the root epidermis, colonizes the roots, occupies the stele, and attacks xylem vessels which cause yellowing, shriveling, and the death of an infected plant (Olivain & Alabouvette, 1999)

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