Identification of an Endophytic Antifungal Bacterial Strain Isolated from the Rubber Tree and Its Application in the Biological Control of Banana Fusarium Wilt.

Deguan Tan,Jiaming Zhang,Lili Fu,Bingyin Han,Xuepiao Sun,Peng Zheng,Xianlong Zhang

doi:10.1371/journal.pone.0131974

Deguan Tan, Jiaming Zhang + Show 5 more

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https://doi.org/10.1371/journal.pone.0131974

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Journal: PloS one	Publication Date: Jul 2, 2015
Citations: 31	License type: CC BY 4.0

Affiliation: Chinese Academy of Tropical Agricultural Sciences

Abstract

Banana Fusarium wilt (also known as Panama disease) is one of the most disastrous plant diseases. Effective control methods are still under exploring. The endophytic bacterial strain ITBB B5-1 was isolated from the rubber tree, and identified as Serratia marcescens by morphological, biochemical, and phylogenetic analyses. This strain exhibited a high potential for biological control against the banana Fusarium disease. Visual agar plate assay showed that ITBB B5-1 restricted the mycelial growth of the pathogenic fungus Fusarium oxysporum f. sp. cubense race 4 (FOC4). Microscopic observation revealed that the cell wall of the FOC4 mycelium close to the co-cultured bacterium was partially decomposed, and the conidial formation was prohibited. The inhibition ratio of the culture fluid of ITBB B5-1 against the pathogenic fungus was 95.4% as estimated by tip culture assay. Chitinase and glucanase activity was detected in the culture fluid, and the highest activity was obtained at Day 2 and Day 3 of incubation for chitinase and glucanase, respectively. The filtrated cell-free culture fluid degraded the cell wall of FOC4 mycelium. These results indicated that chitinase and glucanase were involved in the antifungal mechanism of ITBB B5-1. The potted banana plants that were inoculated with ITBB B5-1 before infection with FOC4 showed 78.7% reduction in the disease severity index in the green house experiments. In the field trials, ITBB B5-1 showed a control effect of approximately 70.0% against the disease. Therefore, the endophytic bacterial strain ITBB B5-1 could be applied in the biological control of banana Fusarium wilt.

Highlights

Banana is among the most important food and fruit crops in many developing countries [1]
The pathogen of banana Fusarium wilt was identified as a soil-borne hyphomycete, Fusarium oxysporum formae specialis cubense (FOC) [4,5,6], and was classified into four physiological races based on virulence to host cultivars in the field [7, 8], including FOC1, FOC2, FOC3, and formae specialis cubense Race 4 (FOC4)
The bacterial strain ITBB B5-1 was isolated from sterilized stem segments of the rubber tree

Summary

Introduction

Banana is among the most important food and fruit crops in many developing countries [1]. Fusarium wilt ( known as Panama disease) is one of the most notorious and destructive diseases in banana [3]. It has been reported in all banana-producing countries, including Asia, Central and South America, Africa, and Australia [4]. The pathogen of banana Fusarium wilt was identified as a soil-borne hyphomycete, Fusarium oxysporum formae specialis cubense (FOC) [4,5,6], and was classified into four physiological races based on virulence to host cultivars in the field [7, 8], including FOC1, FOC2, FOC3, and FOC4. FOC1 infects the cultivars Gros Michel (AAA group), Silk (AAB group), and Pisang Awak (ABB group); FOC2 infects Bluggoe (ABB group) and its close relatives; FOC3 infects Heliconia spp.; and FOC4 infects Cavendish cultivars (AAA group) and all the cultivars susceptible to FOC1 and FOC2 [8]

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