Native Endophytic Pseudomonas putida as a Biocontrol Agent against Common Bean Rust Caused by Uromyces appendiculatus

Abstract

This study aimed to evaluate the efficacy of endophytic bacterium to control common bean rust disease under greenhouse conditions. Endophytic bacterium Pseudomonas putida ASU15 was isolated from fresh asymptomatic common bean, identified using biochemical and molecular characteristics. In vitro, the inhibitory effect of different concentrations of P. putida (1 × 104, 1 × 105 and 1 × 106), as well as fungicide ortiva (0.01%) on uredospores germination of Uromyces appendiculatus were tested using water agar medium. The concentration showing the highest reduction of uredospores germination was at 1 × 106, while there was complete inhibition of uredospores germination associated with using ortiva. Scanning electron microscope exhibited the ability of P. putida cells to attack the cell wall of the fungal uredospores germ tubes of U. appendiculatus, causing obvious cell wall breakdown. The activities of chitinase, lipase, and protease produced by P. putida ASU15, in vitro, were evaluated spectrophotometrically. Chitinolytic, proteolytic, and lipolytic activities were exhibited, contributing 55.26, 3.87, and 26.12 U/mL, respectively. Under greenhouse conditions, treated plants with P. putida ASU15 (two days before pathogen inoculation or at the same time of pathogen inoculation) or fungicide reduced the disease severity, compared to the control. Applying P. putida ASU15 at the same time of pathogen inoculation showed reduction in disease severity (69.9%), higher than application before pathogen inoculation (54.9%). This study is considered the first report that demonstrates the mycoparasitic strategy of P. putida for controlling U. appendiculatus. In conclusion, our results revealed that P. putida ASU15 affords a significant disease reduction that may be attributed to direct suppression of pathogen spores germination.

Potential of Biotic and Abiotic Inducers of Eliciting Systemic Resistance in Snap Bean (Phaseolus vulgaris L.) in Controlling Rust Caused by Uromyces appendiculatus

“…Mizubuti et al (1995) and Zyton and Hassan (2017) tested the ability of the tested bio-agents, B. subtilis and B. thuringiensis and significantly caused reduction in the germination of U. appendiculatus uredospores. The obtained data also are in harmony with those reported by Ismail and Afifi (2019) and Abo-Elyousr et al (2021) who indicated that uredospore germination of U. appendiculatus in vitro were affected by the biotic and abiotic factors, also these results agree with those obtained by Abeysinghe (2009) who mentioned that the use of rhizobacteria reduce U. appendiculatus uredospore germination.…”

Screening of endophytic bacteria from potato tubers and their antagonistic activity against soil-borne potato pathogens

“…The selected isolates could be 10 grouped into four genera, i.e., Bacillus (4 strains), Klebsiella (1 strain), Pseudomonas (2 strains) and Xanthomonas (1 strain). Similarly, other researchers have done reports about the isolation of endophytic bacteria from maize, 27 carrots, 28 common bean, 29,30 and sugar beet. 31 There was significant diversity in the types of endophytes bacteria, both genotypic and phenotypic.…”

Culturable bacterial endophytes of Aconitum carmichaelii Debx. were diverse in phylogeny, plant growth promotion, and antifungal potential

“…Endophytic B. subtilis, B. velezensis, Leuconostoc mesenteroides , and Lactococcus lactis were capable of controlling the bacterial wilt of tomato (Dowarah et al, 2021 ). Native endophytic P. putida afforded a significant reduction in common bean rust caused by Uromyces appendiculatus (Abo-Elyousr et al, 2021 ). In the current study, 20 out of 124 bacterial endophytes exhibited good antagonistic activities against S. rolfsii and F. oxysporum both in vitro and on root slices ( Table 3 ).…”

“…Chitinophaga and Flavobacterium were enriched by sugar beet to suppress the root pathogen Rhizoctonia solani (Carrion et al, 2019 ). The mechanisms for plant growth promotion by bacterial endophytes involve the acquisition of nutrients such as nitrogen, phosphate, potassium, and iron and the production of plant hormones such as auxin, cytokinin, or ethylene (Santoyo et al, 2016 ; Wu et al, 2021 ), while the production of hydrolytic enzymes and antimicrobial metabolites such as antibiosis and volatile organic compounds and induction of systemic resistance are mechanisms employed by bacterial endophytes for plant protection against pathogens (Abo-Elyousr et al, 2021 ; Wang et al, 2021 ; Dimkić et al, 2022 ).…”