Plant Beneficial Bacteria as Bioprotectants against Wheat and Barley Diseases

Abstract

Wheat and barley are the main cereal crops cultivated worldwide and serve as staple food for a third of the world’s population. However, due to enormous biotic stresses, the annual production has significantly reduced by 30–70%. Recently, the accelerated use of beneficial bacteria in the control of wheat and barley pathogens has gained prominence. In this review, we synthesized information about beneficial bacteria with demonstrated protection capacity against major barley and wheat pathogens including Fusarium graminearum, Zymoseptoria tritici and Pyrenophora teres. By summarizing the general insights into molecular factors involved in plant-pathogen interactions, we show to an extent, the means by which beneficial bacteria are implicated in plant defense against wheat and barley diseases. On wheat, many Bacillus strains predominantly reduced the disease incidence of F. graminearum and Z. tritici. In contrast, on barley, the efficacy of a few Pseudomonas, Bacillus and Paraburkholderia spp. has been established against P. teres. Although several modes of action were described for these strains, we have highlighted the role of Bacillus and Pseudomonas secondary metabolites in mediating direct antagonism and induced resistance against these pathogens. Furthermore, we advance a need to ascertain the mode of action of beneficial bacteria/molecules to enhance a solution-based crop protection strategy. Moreover, an apparent disjoint exists between numerous experiments that have demonstrated disease-suppressive effects and the translation of these successes to commercial products and applications. Clearly, the field of cereal disease protection leaves a lot to be explored and uncovered.

Diversity and Exploration of Endophytic Bacilli for the Management of Head Scab (Fusarium graminearum) of Wheat

“…Head scab (HS) is acknowledged as one of the prime diseases of wheat because of its global presence in all wheat-growing countries and is ranked as the fourth biggest threat to successful quality wheat production [ 49 ]. Due to the unavailability of completely resistant cultivars, the management of HS is heavily relying on fungicides.…”

Beneficial Microorganisms as Bioprotectants against Foliar Diseases of Cereals: A Review

“…By integrating the hcnABC gene cluster from P. fluorescens CHAO, pleiotropic mutants were derived, resulting in HCN-overproducing derivatives. In the absence of antibiotics and siderophores, overproduction of HCN by this bacterium resulted in a minor but statistically significant increase in the suppression of symptoms caused by P. recondita and Z. tritici on wheat seedling leaves [ 128 , 159 ]. Similarly, other plant pathogenic bacteria and fungi were suppressed in vitro by P. fluorescens PFM2, which also attacks S. tritici .…”

Mycorrhizal Association and Plant Disease Protection: New Perspectives

“…The effects of AM symbiosis on plant interactions with other organisms, such as the induction of resistance against plant pathogens, seem to result from the combination of multiple mechanisms that may operate simultaneously [125]. A proposed hypothesis is that colonization of roots by AM fungi primes defense mechanisms, leading to mycorrhiza-induced resistance (MIR) [126] by the activation of MAMP-triggered immunity (MTI) [127]. MIR is a low-cost type of induced resistance that may be among the reasons to explain why root associations with AM fungi have been conserved during evolution and are widespread among species [128,129].…”