An Extract Purified from the Mycelium of a Tomato Wilt-Controlling Strain of Fusarium sambucinum Can Protect Wheat against Fusarium and Common Root Rots

Abstract

An approach to manage seed-transmitted Fusarium crown-foot-root rot (FCR, Fusarium spp.) and common root rot (CRR, Bipolaris sorokiniana) on wheat, avoiding environmental risks of chemicals, is seed treatments with microbial metabolites. F. sambucinum strain FS-94 that induces resistance to tomato wilt was shown by this study to be a source of non-fungitoxic wheat-protecting metabolites, which were contained in a mycelium extract purified by gel-chromatography and ultrafiltration. Plant-protecting effect of the purified mycelial extract (PME) was demonstrated in vegetation experiments using a rolled-towel assay and by small-plot field trials. To elucidate mechanisms putatively underlying PME protective activity, tests with cultured Triticum aestivum and T. kiharae cells, particularly the extracellular alkalinization assay, as well as gene expression analysis in germinated wheat seeds were used. Pre-inoculation treatments of seeds with PME significantly decreased the incidence (from 30 to 40%) and severity (from 37 to 50%) of root rots on seedlings without any inhibition of the seed germination and potentiation of deoxynivalenol (DON), DON monoacetylated derivatives and zearalenon production in FCR agents. In vegetation experiments, reductions in the DON production were observed with doses of 0.5 and 1 mg/mL of PME. Pre-sowing PME application on seeds of two spring wheat cultivars naturally infected with FCR and CRR provided the mitigation of both diseases under field conditions during four growing seasons (2013–2016). PME-induced ion exchange response in cultured wheat cells, their increased survivability, and up-regulated expression of some defensins’ genes in PME-exposed seedlings allow the suggestion of the plant-mediated character of disease-controlling effect observed in field.

Effective Zearalenone Degradation in Model Solutions and Infected Wheat Grain Using a Novel Heterologous Lactonohydrolase Secreted by Recombinant Penicillium canescens

“…After an overnight incubation at 30 • C at a slight automated agitation, acetonitrile was added to a final concentration of 84%, and the suspensions were extracted at vigorous shaking for 30 min. ZEN was further purified from the extract as described earlier [60]. The precipitate obtained after the evaporation of the purified ZEN-containing extract on a rotary evaporator was dissolved in a minimum volume of a methanol-acetonitrile mixture (1:1) and analyzed by reversed-phase HPLC.…”

Studying the Ability of Thymol to Improve Fungicidal Effects of Tebuconazole and Difenoconazole Against Some Plant Pathogenic Fungi in Seed or Foliar Treatments

“…The highest concentration of difenoconazole in our experiments reflected the commercial fungicidal dosage recommended for grain treatments with Dividend R to protect wheat and barley plants against Fusarium and common *Seeds were surface-disinfect before treatments as described earlier (Shcherbakova et al, 2018). **Non-disinfect seeds naturally infected by fungal root rot agents.…”

“…Upon completion of the cultivation, DON and ZEN were quantified by reverse phase HPLC using a Waters 1525 Breeze HPLC system equipped with a Waters 2487 UV detector, applying isolation procedures slightly modified from those described previously (Shcherbakova et al, 2018;Stakheev et al, 2018). Briefly, the submerged culture of each experimental or control flask was extracted twice with an equal volume of ethyl acetate or dichloromethane (to isolate ZEN or DON, respectively) for 1-h on an incubator shaker at 220 rpm and 25 • C. Mycelia were separated by centrifugation and dried at 102 • C up to a constant weight.…”

Defensin-like peptides in wheat analyzed by whole-transcriptome sequencing: a focus on structural diversity and role in induced resistance

“…The protective effect of the resistance-inducing metabolites from F. sambucinum (isolate FS-94) was assayed as described (Shcherbakova et al, 2018). Briefly, 50 surface-sterilized T. kiharae seeds were incubated in the FS-94 elicitor metabolites for 3 h as described above and infected with F. oxysporum by soaking in the fungal spore suspension for 30 min, whereupon, seeds were placed on filter paper towels, which were rolled up and put in beakers with distilled water.…”

“…Earlier, we showed that the intracellular elicitor metabolites produced by the biocontrol Fusarium sambucinum (isolate FS-94) protect wheat from Stagonospora nodorum causing glume/leaf blotch as well as from multiple fungi belonging to the pathogenic root rot complex ( F. culmorum , F. avenaceum , F. oxysporum , F. sporotrichioides , F. gibbosum , and Bipolaris sorokiniana ) (Shcherbakova et al, 2012; Shcherbakova et al, 2018) and induce systemic resistance in plants (Shcherbakova et al, 2011; Shcherbakova et al, 2018). In this work, to further analyze the mode of action of the resistance elicitors from F. sambucinum and to elucidate the role of defensins, one of the most important AMP family, in induced resistance (IR), we used global transcriptome sequencing (RNA-seq) of wheat seedlings treated with the elicitors and displaying IR.…”