Fluopyram Sensitivity and Functional Characterization of SdhB in the Fusarium solani Species Complex Causing Soybean Sudden Death Syndrome

• Published in: Frontiers in microbiology 2018-10, Vol.9, p.2335-2335
• Main Authors: Sang, Hyunkyu, Witte, Alexander, Jacobs, Janette L, Chang, Hao-Xun, Wang, Jie, Roth, Mitchell G, Chilvers, Martin I
• Format: Article
• Language: English
• Subjects: fluopyram; Fusarium brasiliense; Fusarium tucumaniae; Fusarium virguliforme; Microbiology; root rot; SdhB
• ISSN: 1664-302X; 1664-302X
• DOI: 10.3389/fmicb.2018.02335

The succinate dehydrogenase inhibitor (SDHI) fungicide, fluopyram, is used as a soybean seed treatment to manage , the casual agent of sudden death syndrome (SDS). More recently, other species within clade 2 of the species, in South America and in America and Africa, have been recognized as additional agents capable of causing SDS. To determine if fluopyram could be used for management of SDS caused by these species, sensitivity tests of the three species to fluopyram were conducted. The mean EC values of and strains to fluopyram were 1.96 and 2.21 μg ml , respectively, but interestingly strains were highly sensitive (mean EC = 0.25 μg ml ) to fluopyram compared to strains of the other two species. A sequence analysis of genes of strains revealed that the strains contain an arginine at codon 277 in the B gene instead of a glycine as in other species. Replacement of glycine to arginine in SdhB-277 in a wild-type strain Mont-1 through genetic transformation resulted in increased sensitivity to two SDHI fungicides, fluopyram and boscalid. Similar to a strain, the Mont-1 (SdhB ) mutant caused less SDS and root rot disease than Mont-1 on soybean seedlings with the fluopyram seed treatment. Our study suggests the amino acid difference in the SdhB in results in fluopyram being efficacious if used as a seed treatment for management of , which is the most abundant SDS causing species in South America. The establishment of baseline sensitivity of species to fluopyram will contribute to effective strategies for managing diseases in soybean and other pathosystems such as dry bean.