Isolation of antagonistic microoganisms against some plants fungal pathogens and evaluation of their activity in vitro and in vivo

Abstract

Cuưently, over 80,000 species of fungi are known to be pathogenic to plants, among them F.oxysporum, F.solani, Phytophthora sp are the most damaging species, that they can destroy the entire crop of important cultivated plants such as pepper, coffee, tomatoes ... With the rapid development of science and technology, many scientists around the world have investigated biological measures for application in plant pest control, using antagonistic activity of fungi, bacteria, and actinomycetes for eliminating of plant harmful diseases. In this study, 37 bacterial strains and 10 aciinomycete strains were isolated from soil and root samples of diseased pepper plants in Quang Tri province and their growth inhibitory activity against some fungal plant pathogens was evaluated by agar diffusion method. The obtained results showed that 31 bacterial isolates and 5 actinomycete isolates antagonized F. oxysporum, all 37 bacterial isolates and 2 aclinomyceie isolates inhibited F. sonaii growth, 10 bacterial isolates and 6 aclinomycete isolates exhibited antagonistic activity against Phyiophthora sp. Using sequencing technique 16S rRNA gene or Kit API, 5 bacterial strains and 2 actinomycetes isolates with highest antagonistic activity were identified as PaenibaciUus sp; Paenibaciỉìus xyìaniìyticus. Bacillus sublilis, Burkholderia cepacia, Pseudomonas luteola: Strepiomyces diastatochromogenes, and Streptomyces antimycoiicus. Antagonistic activity of selected strains against F. oxysporum in vivo in laboratory conditions on tomato plant was determined. The obtained results show that selected strains not only capable of inhibiting the F.oxysporum growth, but also can stimulate the growth of tomato plants in laboratory conditions.