Additive Effect of the Composition of Endophytic Bacteria Bacillus subtilis on Systemic Resistance of Wheat against Greenbug Aphid Schizaphis graminum Due to Lipopeptides

Abstract

The use of biocontrol agents based on endophytic bacteria against phloem-feeding insects is limited by a lack of knowledge and understanding of the mechanism of action of the endophyte community that makes up the plant microbiome. In this work, the mechanisms of the additive action of endophytic strains B. subtilis 26D and B. subtilis 11VM on the resistance of bread spring wheat against greenbug aphid Schizaphis graminum, was studied. It was shown that B. subtilis 26D secreted lipopeptide surfactin and phytohormones cytokinins, and B. subtilis 11VM produced iturin and auxins into the cultivation medium. Both strains and their lipopeptide-rich fractions showed direct aphicidal activity against greenbug aphid. For the first time, it was shown that B. subtilis 26D and B. subtilis 11VM in the same manner, as well as their lipopeptide-rich fractions, activated the expression of salicylate- and ethylene-dependent PR genes, and influenced plant redox metabolism, which led to an increase in plant endurance against aphids. The composition of endophytic strains B. subtilis 26D + B. subtilis 11VM had an additive effect on plant resistance to aphids due to an increase in the number of endophytic bacterial cells, and, as well as due to the synergistic effect of their mixture of lipopeptides − surfactin + iturin, both on the aphid mortality and on the expression of PR1 and PR3 genes. All these factors can be the reason for the observed increase in the growth of plants affected by aphids under the influence of B. subtilis 26D and B. subtilis 11VM, individually and in composition. The study demonstrates the possibility of creating in the future an artificial composition to enhance plant microbiome with endophytic bacteria, which combines growth-promoting and plant immunity stimulating properties against phloem-feeding insects. This direction is one of the most promising approaches to green pesticide discovery in the future.

Search for biocontrol agents among endophytic lipopeptidesynthesizing bacteria <i>Bacillus</i> spp. to protect wheat plants against Greenbug aphid (<i>Schizaphis graminum</i>)

“…), 2020, which was maintained under laboratory-controlled conditions on plants of common spring wheat (Triticum aestivum L.) cv. Salavat Yulaev (SY) as described previously (Rumyantsev et al, 2023). Seeds of cv.…”

“…Experimental conditions. Before planting, some wheat seeds were treated with a liquid culture of bacteria in a semidry manner at growth-stimulating concentrations selected earlier (Alekseev et al, 2021;Rumyantsev et al, 2023). The cell titer in the suspension was counted at 600 nm using a SmartSpectm Plus spectrophotometer (Bio-Rad, USA) certified for this task.…”

“…The elicitor role of lipopeptides against a wide range of pathogens of plants has been shown in many studies (Tunsagool et al, 2019;Jiang et al, 2021). However, information on the elicitor role of lipopeptides in triggering ISR in plants against sucking insects is limited (Rashid et al, 2018;Rumyantsev et al, 2023).…”

Novel Sources of Resistance to Stagonospora nodorum and Role of Effector-Susceptibility Gene Interactions in Wheat of Russian Breeding

“…To standardize the data, the wheat gene TaRLI (RNaseLinhibitor-like) (Table S2, Supplementary Materials) was used as an internal reference [27]. The delta-delta Ct method was used to quantify the relative gene expression [28,29]. Three independent biological and three technical replications were performed for each experiment.…”

Examining Innovative Technologies: Nano-Chelated Fertilizers for Management of Wheat Aphid (Schizaphis graminum Rondani)

“…Considering that research on S. graminum has been ongoing for several years and most reports on its pathogenicity date back to past years, recent studies continue to focus on its control and life cycle, highlighting the significance of this pest. Recent studies have primarily focused on controlling the wheat aphid through various approaches, including the use of Bacillus subtilis [ 11 ], predators such as ladybirds [ 12 ], soil amendments [ 13 ], insecticides [ 14 ], as well as genetic resistance techniques like QTL mapping [ 15 ]. Recently, the use of nano-materials as another component of integrated pest management, aiming to enhance plant resistance and weaken pest infestation, has received significant attention [ 16 ].…”