Plant growth-promoting rhizobacteria (PGPR): their potential as antagonists and biocontrol agents

Abstract

Bacteria that colonize plant roots and promote plant growth are referred to as plant growth-promoting rhizobacteria (PGPR). PGPR are highly diverse and in this review we focus on rhizobacteria as biocontrol agents. Their effects can occur via local antagonism to soil-borne pathogens or by induction of systemic resistance against pathogens throughout the entire plant. Several substances produced by antagonistic rhizobacteria have been related to pathogen control and indirect promotion of growth in many plants, such as siderophores and antibiotics. Induced systemic resistance (ISR) in plants resembles pathogen-induced systemic acquired resistance (SAR) under conditions where the inducing bacteria and the challenging pathogen remain spatially separated. Both types of induced resistance render uninfected plant parts more resistant to pathogens in several plant species. Rhizobacteria induce resistance through the salicylic acid-dependent SAR pathway, or require jasmonic acid and ethylene perception from the plant for ISR. Rhizobacteria belonging to the genera Pseudomonas and Bacillus are well known for their antagonistic effects and their ability to trigger ISR. Resistance-inducing and antagonistic rhizobacteria might be useful in formulating new inoculants with combinations of different mechanisms of action, leading to a more efficient use for biocontrol strategies to improve cropping systems.

Bio-suppression of Sclerotinia Stem Rot of Tomato and Biostimulation of Plant Growth Using Tomato-associated Rhizobacteria

“…PGPR are highly diverse and are widely used as biocontrol agents against various plant diseases. Their disease-suppressive effects may be achieved via local antagonism toward soil borne pathogens or through induction of systemic acquired resistance against pathogens throughout the entire plant [28,29].…”

Activity of rhizobacteria of Jatropha curcas against Fusarium verticillioides and Leptoglossus zonatus

“…(Beneduzi, Ambrosini, & Passaglia, 2012). In particular, in the rhizosphere of J. curcas bacteria have been isolated from the genera Enterobacter, Bacillus and Pseudomonas with the aim of promoting plant growth, but without evaluating the antifungal activity of these rhizobacteria (Jha, Patel, & Saraf, 2012;Patel & Saraf, 2013); therefore, the results obtained in this study are of interest for the management of fungal diseases of a crop.…”

“…However, it has been reported that some Bacillus species are able to Mitchell, Snook, & Olubajo, 2012). La rizobacteria B. mojavensis posee un mecanismo antagonista complejo aún no conocido por completo, donde además de producir los compuestos mencionados se relaciona también la producción de surfactinas con la actividad antifúngica (Bacon et al, 2012 (Beneduzi, Ambrosini, & Passaglia, 2012). En particular, en la rizósfera de J. curcas se han aislado bacterias del género Enterobacter, Bacillus y Pseudomonas con el objetivo de promover el crecimiento vegetal, pero sin evaluar la actividad antifúngica de estas rizobacterias (Jha, Patel, & Saraf, 2012;Patel & Saraf, 2013); por tanto, los resultados obtenidos en esta investigación son de interés para el manejo de enfermedades fúngicas del cultivo.…”

Improved potato microclonal reproduction with the plant growth-promoting rhizobacteria Azospirillum

“…They also participate in the competitive bioregulation of soil microbial associations (Beneduzi et al 2012) and induce systemic resistance in the macroorganisms to abiotic and biotic environmental factors (Zamiodis and Pieterse 2012;Paul and Lade 2014). Prominent among them are associative bacteria of the genus Azospirillum, which, in particular, can enhance the growth and development of potato microclones in vitro (Volkogon et al 2006), improve the acclimation of fruit plants ex vitro (Vettori et al 2010), and increase the productivity of agricultural plants in vivo (Bashan and de-Bashan 2010;Fibach-Paldi et al 2012).…”