Abstract
BackgroundFungal stem end rot disease of pitaya caused by Alternaria alternata is one of the most destructive diseases in Binh Thuan province, Vietnam. This study aimed to assess the antagonistic effects of some endophytic bacteria isolated from the weed plant (Echinochloa colonum) against A. alternata.ResultsA total of 19 endophytic bacteria were isolated and 5 of them presented in vitro antagonistic activity against A. alternata. Of five, strain EC80 significantly inhibited the pathogenic growth with a mean inhibition diameter of 11.88 ± 0.08 mm, while the other four (C79, EC83, EC90, and EC97) showed a weak inhibition. Interestingly, the combination of EC79 and EC80 reduced more biomass of pathogenic fungi than the single one did. EC79 showed positive results for amylase, indole acetic acid (IAA), and biofilm production, whereas EC80 presented positive capabilities for IAA and biofilm production and a negative one for amylase production. In addition, the combined filtrate of EC79 and EC80 presented non-antifungal activity on biocontrol tests in vitro, indicating that bacteria cells played a role in defending against the pathogen. Moreover, both isolates EC79 and EC80 significantly increased seedling biomass than the control.ConclusionsThe results suggest that those two strains in combination had the potential to be used as a biocontrol agent against A. alternata. More studies should be done in the future to evaluate their efficiency under the field conditions.
Highlights
Fungal stem end rot disease of pitaya caused by Alternaria alternata is one of the most destructive diseases in Binh Thuan province, Vietnam
Endophytic bacteria were isolated from the weed (E. colonum) to explore their potential as a biological agent in the integrated management of stem end rot caused by A. alternata
The present study showed that the combination of EC79 + EC80 strains generated a better antagonist for A. alternata clarifying the microbial synergism in inhibiting the pathogenic fungi, which is consistent with previous researches on combinations of biocontrol agents (Guetsky et al 2007; Xu et al 2010; Shen et al 2020)
Summary
Fungal stem end rot disease of pitaya caused by Alternaria alternata is one of the most destructive diseases in Binh Thuan province, Vietnam. This study aimed to assess the antagonistic effects of some endophytic bacteria isolated from the weed plant (Echinochloa colonum) against A. alternata. The pest takes a part in decreasing productivity and the quality of products, especially the stem end rot diseases that are caused by the fungus, Alternaria sp. Echinochloa colonum is a weed plant that has a wide range of habitats such as cultivated areas, waste grounds, ditches, and fields. It forms an important association with 35 crops in more than 60 countries (Rao et al 2007). E. colonum has a rapid growth, a great competitive ability, and a severe infestation leading to substantial crop yield reductions This might be the result of endophytic bacterial associates. The application of weed endophytic bacteria in the biocontrol of plant diseases for sustainable agriculture can be a very promising tool because of their short lifecycle and high selection of antagonistic form
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