Aspergillus flavus YRB2 from Thymelaea hirsuta (L.) Endl., a non-aflatoxigenic endophyte with ability to overexpress defense-related genes against Fusarium root rot of maize

Abstract

Fusarium root rot, caused by Fusarium solani (Mart.) Sacc., represents one of the most damaging diseases of maize affecting plant growth and yield. In this study, the antagonistic potential of a non-aflatoxigenic endophytic Aspergillus flavus YRB2, isolated from Thymelaea hirsuta (L.) Endl., was tested against F. solani in vitro. In addition, its biocontrol activity against Fusarium root rot of maize was evaluated under greenhouse conditions. Its impacts on plant molecular, pathological, physiological, and growth levels were also studied. Results obtained revealed a potent antagonistic behavior for A. flavus YRB2 against F. solani in vitro, recording 80% growth inhibition. Seventeen secondary metabolites were detected in the n-hexane extract of A. flavus YRB2 filtered culture broth using GC-MS analysis. Among them, various antifungal secondary metabolites were produced, namely palmitic acid, α-linolenic acid, stearic acid, 2, 4-di-tert-butylphenol, diisobutyl phthalate, and heneicosane. In contrast, HPLC analysis showed that no aflatoxins (B1, B2, G1, and G2) were detected. Under greenhouse conditions, colonization of maize plants with A. flavus YRB2 exhibited a potential biocontrol activity against Fusarium root rot, recording 73.4% reduction in the disease severity. Triggering of transcriptional expression level of the defense-related genes JERF3 (7.2-fold), CHI II (8-fold), and POD (9.1-fold) was reported, indicating the inducing effect on the plant immunity. In addition, an increment in the antioxidant enzymes POD and PPO, and the total phenolic content in maize roots was also observed in response to this treatment. Moreover, a growth-promoting effect was also observed for colonization of maize plants with A. flavus YRB2. Based on the obtained data, we can conclude that A. flavus YRB2 may represent a promising biocontrol and growth-promoting agent for maize plants against Fusarium root rot. Nevertheless, field evaluation is highly requested before the use recommendation.

Bio-stimulating effect of endophytic Aspergillus flavus AUMC 16068 and its respective ex-polysaccharides in lead stress tolerance of Triticum aestivum plant

“…Endophytic microorganisms are promising resources of biofertilizers, natural antimicrobial compounds, and growth promotors, which can be used as green advances to reduce the use of agrochemicals 71 , 72 . Other researchers have confirmed similar findings, demonstrating the beneficial effects of endophytic microorganisms where it is important for developing feasible replacements for chemicals like fungicides and insecticides, as well as the recurrent problems of their uncritical use and could apply the endophytes for plant growth promotion and prevention of fungal infections 73 , 74 . The plant growth-promoting abilities of endophytic fungus, and recent advances in our knowledge of some of the mechanisms, imply that this interesting source warrants additional exploration for possible future use in agriculture.…”

Combined interaction between the diazotrophic Niallia circulans strain YRNF1 and arbuscular mycorrhizal fungi in promoting growth of eggplant and mitigating root rot stress caused by Rhizoctonia solani

“…The JERF3 gene was particularly expressed in response to treatment of eggplants with N. circulans YRNF1 and AMF. The gene JERF3 controls several plant defense genes (Rashad et al, 2022b). PAL1 regulates the main step in the polyphenolic biosynthetic pathway, through conversation of phenylalanine to t-cinnamic acid (Mouradov and Spangenberg, 2014).…”

“…Triggering immunity-related genes in plants is an important mode of action of biocontrol agents. Jasmonic acid and ethylene-response factor 3 gene (JERF3), the responsive gene that manages several defence-response genes through the jasmonate/ethylene signalling path-way, is elicited by abiotic and biotic plant stresses (Rashad et al, 2022b).…”

Fusarium Induced Anatomical and Biochemical Alterations in Wild Type and DPA-treated Wheat Seedlings

“…39 The VBs of WT and DPA were damaged and collapsed due to fungal growth, similarly, the roots and stems of corn plants were infected by a pathogenic strain of F. verticillioides. 40 In addition, the sclerenchyma cells provide mechanical support to VBs through thickening primary cell walls, which further acts as a mechanical barrier against fungal invasion. The present study revealed higher numbers of sclerenchyma cells in WT as compared to DPA during Fusarium infection.…”