Phytophthora Antagonism of Endophytic Bacteria Isolated from Roots of Black Pepper (Piper nigrum L.)

Abstract

In this study, 90 root samples were collected from 30 black pepper farms in three provinces in the Central Highlands of Vietnam. A total of 352 endophytic bacteria were isolated and their morphology described. An in vitro assay on the antifungal activity of these isolates was then conducted and 47 isolates were found to have antagonistic activity on Phytophthora fungi. The antifungal activity of the 47 isolates was evaluated in vivo by shoot assay. Among these 47 isolates, 6 were selected for further investigation. The six isolates were classified and identified by sequencing the 16S RNA gene and phylogeny. The results showed that all six endophytic bacteria belong to the following species of Bacillus genus: B. siamensis, B. amyloliquefaciens, B. velezenis, and B. methylotrophiycus. Enzymatic activity related to the antifungal activity of the six potent isolates was determined; it showed that they possessed high chitinase and protease activities. These isolates were applied for black pepper seedlings in greenhouse. The results showed three promising isolates: B. siamensis EB.CP6, B. velezensis EB.KN12, and B. methylotrophycus EB.KN13. Black pepper seedlings treated with the promising bacteria had the lowest rate of root disease (8.45-11.21%) and lower fatal rate (11.11-15.55%) compared to the control group (24.81% and 24.44%). In addition, the three promising isolates strongly affected the growth of the black pepper seedlings in greenhouse. The plant height, length of roots, and fresh biomass of the seedlings in the treated plots were higher than those in the control plots. Thus, the endophytic bacterial isolates have the potential to act as biocontrol agent for the sustainable production of black pepper.

Combined Application of Rhizosphere Bacteria with Endophytic Bacteria Suppresses Root Diseases and Increases Productivity of Black Pepper (Piper nigrum L.)

“…Interestingly, this strain could inhibit up to 98.8% of Phytophthor growth by producing various enzymes and biochemical compounds; this was confirme by in vivo assays on the black pepper seedlings in the green house. We also carried out phylogenetic analysis of 352 endophytic bacteria isolated from 90 root samples in th farms in the Central Highlands of Vietnam for Phytophthora antagonism under in vitr assay conditions [36]. The results showed that Bacillus velezensis and Bacillus amylolique faciens exhibit pathogenic fungal antagonism and plant growth promotion activities Most studies have reported the results of rhizosphere bacteria and endophytic bacteri on the plant growth promotion and antifungal activity using in vitro or green house-based experiments [8,9,27,28,30,34,36].…”

“…We also carried out phylogenetic analysis of 352 endophytic bacteria isolated from 90 root samples in th farms in the Central Highlands of Vietnam for Phytophthora antagonism under in vitr assay conditions [36]. The results showed that Bacillus velezensis and Bacillus amylolique faciens exhibit pathogenic fungal antagonism and plant growth promotion activities Most studies have reported the results of rhizosphere bacteria and endophytic bacteri on the plant growth promotion and antifungal activity using in vitro or green house-based experiments [8,9,27,28,30,34,36]. To date, few works have researched th impact of rhizosphere bacteria and endophytic bacteria on the growth and disease re sistance of black pepper in the field.…”

Potential Application of Rhizobacteria Isolated from the Central Highland of Vietnam as an Effective Biocontrol Agent of Robusta Coffee Nematodes and as a Bio-Fertilizer

“…Anti-fungal activity of Pseudomonas aeruginosa TUN03 was assessed according to the method per Ngo et al 2020 [33]. A total of 12 fungal pathogen strains (supported from the Institute of Biotechnology and Environment, Tay Nguyen University, Buon Ma Thuot, Vietnam), including Purpureocillium lilacinum F01, Fusarium solani F02, F. solani F03, F. solani F04, Colletotrichum gloeosporioides F05, F. incarnatum F06, Gongronella butleri F07, Pestalotiopsis mangiferae F08, F. incarnatum F09, F. oxysporum F10, Neonectria sp.…”

“…Assessment of in vitro antifungal activity test of Pseudomonas aeruginosa TUN03 against various plant-pathogen fungal strains. : the activity was observed but not clear for harvesting the data based on the method reported by Ngo et al 2020[33]. All the experiments were performed in triplicate.…”

Endophytic Microorganisms as an Alternative for the Biocontrol of Phytophthora spp.

“…The zoospores were not able to germinate when they were cultured in the presence of this compound. Ngo et al, (2020) [52] isolated endophytic black pepper bacteria, of which six showed the ability to inhibit the growth of Phytophthora spp. by more than 60%.…”