Submitted to: European Journal of Plant Pathology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/4/2013
Publication Date: 8/1/2013
Citation: Yin, .N., Xiao, C. 2013. Molecular characterization and a multiplex allele-specific PCR method for detection of thiabendazole resistance in Penicillium expansum from apple. European Journal of Plant Pathology. 136:703-713. DOI10.1007/S10658-013-0199-2. Interpretive Summary: Blue mold caused by the fungus Penicillium expansum causes significant losses of apple fruit after harvest. The fungicide thiabendazole (TBZ) is commonly used by fruit packers as a postharvest treatment for control of blue mold in apples, but the fungus can develop resistance to TBZ. We found that TBZ resistance was the result of mutations in a specific gene in the pathogen. We further developed a DNA-based method to detect TBZ resistance in P. expansum. A quick detection of TBZ resistance in the pathogen can help apple growers and packers implement relevant measures for control of blue mold.
Technical Abstract: Thiabendazole (TBZ) is commonly used as a postharvest treatment for control of blue mold in apples caused by Penicillium expansum. Different point mutations in the ß-tubulin gene conferring benzimidazole resistance have been reported in plant pathogens, but molecular mechanisms of TBZ resistance in P. expansum from apple in Washington State are unknown. Determination of TBZ resistance level showed that all 102 TBZ-resistant (TBZ-R) isolates were highly resistant. Sequencing of the majority of the ß-tubulin gene showed that 76 TBZ-R isolates harbored the E198V mutation and 26 harbored the F167Y mutation, and all the sensitive isolates did not possess any of the mutations, indicating that these two point mutations in the ß-tubulin gene were correlated with TBZ resistance in P. expansum from apple in Washington State. There was no association between levels of TBZ resistance and types of point mutations (E198V or F167Y) in the ß-tubulin gene. A multiplex allele-specific PCR assay was developed to detect these two mutations simultaneously. Microsatellite-primed PCR derived presence-absence matrix used to assess the genetic relationship among 56 isolates suggested that the resistance mutations originated several times independently and that there was no correlation between the types of point mutation and the genetic background of the isolates.