PseudomonasandBurkholderiainhibit growth and asexual development ofPhytophthora capsici

Abstract

The objective of this study was to isolate and characterize antagonistic rhizobacteria from chili against a notorious phytopathogen Phytophthora capsici. Among the 48 bacteria isolated, BTLbbc-02, BTLbbc-03, and BTLbbc-05 were selected based on their inhibitory activity against P. capsici. They were tentatively identified as Burkholderia metallica BTLbbc-02, Burkholderia cepacia BTLbbc-03, and Pseudomonas aeruginosa BTLbbc-05, respectively, based on their 16S rRNA gene sequencing. All inhibited the growth of P. capsici at varying levels by inducing characteristic morphological alterations of P. capsici hyphae. The cell-free culture supernatant of all three isolates impaired motility (up to 100%) and caused lysis (up to 50%) of the halted zoospores. Bioassays revealed that Pseudomonas sp. had higher antagonism and zoospore motility-inhibitory effects against P. capsici compared with two other isolates, Burkholderia spp. and B. metallica, which caused vacuolation in mycelium. All three bacteria suppressed sporangium formation and zoosporogenesis of P. capsici, and improved the seed germination and growth of cucumber. Our findings suggest that epiphytic bacteria, B. metallica, B. cepacia, and P. aeruginosa, could be used as potential biocontrol agents against P. capsici. A further study is required to ensure conformity with the existing regulations for soil, plant, and human health.

Chitosan biostimulant controls infection of cucumber by Phytophthora capsici through suppression of asexual reproduction of the pathogen

“…Colonies were regularly subcultured by transferring a plug of hyphal tips into a fresh agar plate and incubating it in the same environmental condition mentioned above. To induce sporangia formation, agar cultures from 2-week-old Petri dishes were cut into pieces, covered with sterile distilled water, and kept in Petri dishes at 25°C in the dark [9,13]. To induce zoospore release, cultures with sporangia were placed at 4°C for 30 min, and then incubated at room temperature for another 30 min.…”

“…Phytophthora capsici Leonian is a notorious phytopathogen, which commonly affects cucumber, pepper, tomato, and many other horticultural crops worldwide [9]. It infects the host plants primarily through asexually produced zoospores from the sporangia under favorable environmental condition.…”

“…Novel approaches are required to protect cucumber from the infection by the P. capsici pathogen. Several lines of evidence suggest that probiotic bacteria like Pseudomonas, Bacillus, Burkholderia, etc., are effective in controlling P. capsici [9,13]. But scant information is available on the effect of chitosan biopolymer application on P. capsici growth and disease control in cucumber.…”

Prospect and Challenges for Sustainable Management of Climate Change-Associated Stresses to Soil and Plant Health by Beneficial Rhizobacteria

“…Pathogenic bacteria, fungi, viruses, nematodes, and protists are the major biotic factors affecting agricultural production [95,96]. The PGPR can suppress the growth of phytopathogens and other deleterious microorganisms through antagonism by producing antagonistic substances (i.e., siderophores, antibiotics, hydrogen cyanide, and antimicrobial metabolites), parasitism, competing for nutrients and space, producing various lytic enzymes (e.g., chitinases, glucanases, and proteases), and inducing systemic resistance in plants [8,[97][98][99][100][101][102][103]. The PGPR genera, such as Bacillus, Serratia, Streptomyces, Pseudomonas, Burkholderia, Paenibacillus, Klebsiella, Enterobacter, Alcaligenes, Arthrobacter, Azospirillum, and Azotobacter, are widely utilized to combat the biotic stresses [104][105][106][107].…”

Inhibitory Effect of Trichoderma asperellum Isolate against Ralstonia solanacearum Causing Brinjal Wilt

“…Dual culture was conducted according to Khatun et al (2017). One mycelial disk from the periphery of a 5-day-old TA culture was placed on a PDA plate 3 cm apart from the R. solanacearum inoculation on the same plate.…”