Biolog phenotypic microarray reveals the metabolic substrates required for sclerotial formation of Rhizoctonia solani

Abstract:

Objective To analyze the metabolic substrates required for the sclerotial formation of Rhizoctonia solani and understand the influence of nutritional elements and environmental factors on this process.Methods Biolog phenotypic microarray was used to study the effects of 663 nutritional substances, 96 osmotic environments, and 96 pH environments on the sclerotial formation of R. solani.Results Among the tested nutritional substances and environmental conditions, 19/95 carbon sources, 21/95 nitrogen sources, 16/94 phosphorus and sulfur sources, 69/94 nutritional supplements, 61/282 peptide nitrogen sources, 28/96 osmotic environments, and 40/96 pH environments induced the sclerotial formation of R. solani. Notably, N-acetyl-d-glucosamine, uridine 3′-monophosphate, phosphoryl choline, and five dipeptides (Arg-Trp, Met-Arg, Pro-Phe, Val-Tyr, and Val-Met), as well as three environmental conditions of 10 mmol/L and 20 mmol/L ammonium sulfate at pH 8.0, and pH 4.5+l-proline, significantly induced the sclerotial formation of R. solani. R. solani formed sclerotia in the environments with a broad range of pH 4.0-10.0. The KEGG analysis indicated that the substances inducing sclerotial formation were primarily involved in metabolic pathways, ABC transporters, secondary metabolite biosynthesis, and d-amino acid metabolism.Conclusion Nutrient limitation and environmental stress are key factors inducing the sclerotial formation of R. solani. Under nutrient-restricted conditions, the suitable substances for inducing sclerotial formation include five carbon sources (d-sorbitol, d-xylose, N-acetyl-d-galactosamine, d-arabinose, and d-melezitose), three nitrogen sources (N-acetyl-d-glucosamine, adenosine, and thymidine), two phosphorus sources (uridine 3′-monophosphate and phosphoryl choline), one nutritional supplement (Tween-80), and five peptide nitrogen sources (Arg-Trp, Met-Arg, Pro-Phe, Val-Tyr, and Val-Met). The suitable osmotic environments were 10 mmol/L and 20 mmol/L ammonium sulfate at pH 8.0, and the suitable pH environments were pH 4.0-4.5 and pH 9.5-10.0. These findings provide a foundation for understanding the sclerotial formation mechanism of R. solani.