Biological Control of Rice Bakanae by an Endophytic Bacillus oryzicola YC7007

Abstract

In our previous study, we reported that a novel endophytic bacterium Bacillus oryzicola YC7007 has suppressed bacterial diseases of rice via induced systemic resistance and antibiotic production. This endophytic strain, B. oryzicola YC7007 was used as a biological control agent against bakanae disease of rice caused by Fusarium fujikuroi, and its mechanism of interaction with the pathogen and the rice was further elucidated. Root drenching with B. oryzicola YC7007 suspension reduced the disease severity of bakanae significantly when compared with the untreated controls. The treatments of B. oryzicola YC7007 suspension (2.0 × 107 cfu/ml) to the rice rhizosphere reduced bakanae severity by 46–78% in pots and nursery box tests containing autoclaved and non-autoclaved soils. Moreover, in the detached rice leaves bioassay, the development of necrotic lesion and mycelial expansion of F. fujikuroi were inhibited significantly by spraying the culture filtrate of B. oryzicola YC7007. Drenching of ethyl acetate extracts of the culture filtrate to the rhizosphere of rice seedlings also reduced the bakanae disease severity in the plant culture dish tests. With the root drenching of B. oryzicola YC7007 suspension, the accumulation of hydrogen peroxide was observed at an early stage of rice seedlings, and a hormonal defense was elicited with and without pathogen inoculation. Our results showed that the strain B. oryzicola YC7007 had a good biocontrol activity against the bakanae disease of rice by direct inhibition, and was also capable of inducing systemic resistance against the pathogen via primed induction of the jasmonic acid pathway.

The puzzle of bakanae disease through interactions between Fusarium fujikuroi and rice

“…Several antagonistic microorganisms isolated from different sources have been tested against F. fujikuroi. Grampositive and gram-negative bacteria (Paenibacillus polymyxa from tomato leaves and Bacillus subtilis, B. megaterium, B. oryzicola and Pseudomonas fluorescens from rice) were tested to evaluate their biocontrol potential (65,66,67,68). The antagonistic fungus Trichoderma asperellum was able to penetrate the hyphae of F. fujikuroi and to degrade its cell wall, thus suggesting its biocontrol ability (69).…”

Plant-Growth Promoting Bacillus oryzicola YC7007 Modulates Stress-Response Gene Expression and Provides Protection From Salt Stress

“…We previously reported the isolation and identification of an endophytic bacterium, Bacillus oryzicola YC7007, from the rice (Oryza sativa L.) rhizosphere (Chung et al, 2015). The YC7007 bacteria was found to promote plant growth and act as a biocontrol against fungal and bacterial rice pathogens through induced systemic resistance (ISR) and antibiotic production (Chung et al, 2015;Hossain et al, 2016). In this study, we investigated whether the PGPR B. oryzicola YC7007 ameliorates the adverse effects of high salt stress on the growth of Arabidopsis thaliana plants.…”

Diffusible and Volatile Antifungal Compounds Produced by an Antagonistic Bacillus velezensis G341 against Various Phytopathogenic Fungi

“…One representative candidate is Bacillus species belonging to Gram-positive bacteria. Bacillus species can produce various kinds of diffusible and volatile compounds with strong inhibitory activity against plant pathogens ( Arrebola et al, 2010 ; Almenar et al, 2007 ; Hossain et al, 2016 ; Kim et al, 2015 ; Nam et al, 2016 ; Ongena and Jacques, 2008 ). Among various diffusible compounds, cyclolipopeptides have many advantages compared to chemical surfactants, including low toxicity, high biodegradability, environmentally friendly characteristics ( Ongena and Jacques, 2008 ; Peypoux et al, 1999 ; Yu et al, 2002 ), and low foaming ( Compant et al, 2005 ).…”