Species Identification Of Pathogens Causing Potato Dry Rot And Molecular Detection Of Dominant Pathogen In Hebei And Inner Mongolia

Potato dry rot, caused by various Fusarium spp., is one of the most important storagediseases of potato. Large scale cultivation, mechanized harvest and bulk storage made thisdisease more and more serious and become a main reason of rotten potatoes in the storagecavern. Determining current species of pathogens causing potato dry rot is the premise andbasis of disease control, and rapid detection of pathogens and proper use of effectivefungicide screened have the important practical significance to disease diagnosis andscientific prevention and control. In this study, species of the isolated pathogens in Hebeiand Inner Mongolia were identified by a combination of morphology and phylogeny. Inaddition, a molecular detection of dominant species method was developed and thetoxicities of six fungicides were also tested in laboratory. The main results are summarizedas follows:1. In total of235Fusarium isolates were isolated and purified from300dry rot tuberscollected from Chengde and Zhangjiakou, Hebei province and Hohhot, Inner Mongolia.Four Fusarium species, i.e. F. sambucinum, F. acuminatum, F. oxysporum and F. redolens,were classified and their numbers were149,80,3and3, respectively. F. acuminatum andF. redolens were firstly reported in Hebei, and F. redolens was firstly reported in InnerMongolia. F. sambucinum and F. acuminatum were dominant species in Hebei and theirfrequencies were50.00%and48.68%, respectively. Nevertheless, F. sambucinum wasdominant pathogen in Inner Mongolia and its frequency was87.95%. F. sambucinum wasthe common dominant pathogen of the two provinces.2. Based on the translation elongation factor-1alpha (TEF-1α) sequences of Fusariumgenus, a specific pair of primers Fs-F/Fs-R for F. sambucinum was designed. UsingFs-F/Fs-R, a single unique expected PCR band of309bp in length was amplified from F.sambucinum, while no PCR band could be amplified from other Fusarium species andpathogens causing else potato important disease. The detection sensitivity of genomicDNA was70pg/μL. The potato tubers infected by F. sambucinum also could be detectedthrough this method.3. The toxicities of six fungicides against four pathogens were tested, including fludioxonil, difenoconazole, prochloraz, tebuconazole, cyanoacrylate and hymexazol.Sensitivities to fungicides of different Fusarium species were different. The toxicity ofprochloraz was the strongest and the EC50value was from0.010to0.057μg/mL;cyanoacrylate had no effect on F. sambucinum; the inhibitory effect of hymexazol waspoor generally and its EC50value was between9.340and64.408μg/mL; inhibitory effectof other four fungicides were better relatively. Potato tubers inoculated with F.sambucinum were treated with fungicides, which could inhibit the lesion expansion andinfection of pathogen, but control efficiency of different fungicide was different.Difenoconazole, prochloraz and tebuconazole were better relatively.