Identification and Biological Characteristics of the Red Stele Root Rot Pathogen of Strawberry
A variety of diseases and pests were becoming quite serious with the expanded planting area.Among of them,red stele root rot was one of the most destructive soil borne disease without efficient control strategies,which caused enormous economic losses.This disease was observed on strawberry in greenhouse in Xinkou Town,Xiqing District,Tianjin in March 2023.Large areas of strawberry became wilted and died.The xylem of the main root was found to be turned reddish brown and decayed from root cross-cutting.5 strains with consistent morphological characteristics were isolated from the root tissues of 6 strawberry diseased plants following tissue separation method.The isolated colonies were round,white,with a dark pink color on the back and a light pink color on the edge.Large conidia were sickle shaped,while small conidia were oval shaped.The pathogenicity testing based on Koch's postulates showed that the strain TN97 caused similar symptoms in the stem base and roots of strawberry plants after inoculation.The genomic DNA of the strain TN97 was extracted and PCR was carried on to amplify the rDNA-ITS and EF-1α.BLASTn comparison analysis exhibited that both ITS and EF-1α(with Genebank accession number PP257645 and PP297566)showed 100％similarity with Fusarium prolif-eratum and gathered in the same branch with F.Proliferatum based on phylogenetic analysis.The optimal carbon and nitrogen sources for TN97 growth were sucrose and potassium nitrate.The optimal growth temperature was 25℃ and the optimal growth pH of TN97 was ranged from 8 to 10.In conclusion,this is the first report of F.proliferatum causing red stele root rot on strawberry in Tianjin,which is going to shed light on disease diagnosis and effective control strategies.
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