Isolation and Screening of Antagonistic Endophytes against Phytophthora infestans and Preliminary Exploration on Anti-oomycete Mechanism of Bacillus velezensis 6-5

Abstract

Phytophthora infestans, the notorious pathogen of potato late blight, leads to a severe decline in potato yields and even harvest failure. We isolated 201 endophytic isolates from healthy root tissues of potatoes, among which 41 showed strong antagonistic activity against P. infestans. Further, the tolerance to stress and the potential application against potato late blight of these antagonistic isolates were tested. Most of them were extremely tolerant to stresses such as acid–alkali, temperature, UV, salt, and heavy metal stress. However, some antagonistic isolates with excellent stress tolerance might be pathogenic to potatoes. Combining the screening results, a total of 14 endophytes had excellent comprehensive performance in all the tests. In this paper, the endophyte 6-5 was selected among them for the preliminary exploration of the anti-oomycete mechanism. Analysis of the 16S rDNA sequence revealed that 6-5 had a high homology to the corresponding sequence of Bacillus velezensis (99.72%) from the NCBI database. Endophyte 6-5 significantly inhibited the mycelial growth of P. infestans, with an inhibition rate of over 90% in vitro assays, and deformed the hyphal phenotype of P. infestans. In addition, endophyte 6-5 could secrete protease and cellulase, and produce antagonistic substances with high thermal stability, which might be helpful to its antagonistic activity against P. infestans. Furthermore, it was demonstrated that 6-5 had the ability to improve the resistance of potato tubers to late blight. In short, our study described the process of isolating and screening endophytes with antagonistic activity against P. infestans from potato roots, and further explored the potential of biocontrol candidate strain 6-5 in potato late blight control.

Comparative genomics reveals insight into the phylogeny and habitat adaptation of novel Amycolatopsis species, an endophytic actinomycete associated with scab lesions on potato tubers

“…Comparative smBGCs exhibited a fascinating genetic potential to synthesize different chemical classes of bioactive secondary metabolites and undoubtedly indicated that the distribution patterns of smBGCs are mainly related to species phylogeny. Moreover, strain MEP2-6 T can produce endoglucanase, which is an important enzyme in plant-based biofuels and food-feed industries ( Behera et al., 2017 ), and is also a critical enzyme that inhibits Phytophthora infestans , a causative agent of potato late blight disease ( Zhang et al., 2023 ). Thus, we suggest that A. solani MEP2-6 T could be further investigated as a promising candidate for the discovery of novel bioactive compounds, biotechnological applications, and potato probiotics.…”

In Vitro Evaluation of Some Endophytic Bacillus to Potentially Inhibit Grape and Grapevine Fungal Pathogens

“…Various B. velezensis and B. amyloliquefaciens strains have been reported as well-known biocontrol agents against bacterial, fungal, and viral plant pathogens such as Xanthomonas citri subsp. citri [72], Armillaria solidipes [73], Erysiphe heraclei [74], Phytophthora infestans [75], F. oxysporum f.sp. fragariae [76], F. oxysporum f.sp.…”

Antifungal Activity of Industrial Bacillus Strains against Mycogone perniciosa, the Causative Agent of Wet Bubble Disease in White Button Mushrooms

“…Recently, various mechanisms of phytopathogen suppression by Bacillus strains have been actively studied [ 30 , 31 , 32 , 33 ]. In particular, chitinase and β-1,3-glucanase enzymes produced by B. velezensis CE 100 and the effectively lysing mycelium of Macrophomina phaseolina and Fusarium oxysporum f. sp.…”