Isolation and identification of pathogens of potato early blight and antifungal activity of different plant extract and capillin on pathogens
[Objective]The pathogen of potato early blight in Huize county,Qujing city was identified,and the antifungal activity of different plant extracts and capillin on pathogenic bacteria was explored,which would provide scientific basis for the biological control of potato early blight.[Method]The pathogens were isolated and purified by tissue separation and identified by a combination of morphological and molecu-lar biology.The antifungal activity of extracts was screened by mycelium growth rate method.The antifungal virulence of capillin and its influ-ence on the morphology,dry mass,reduced sugar and total protein content were determined.[Result]The pathogenic bacteria isolated and pu-rified from potato diseased leaves in Huize county,Qujing city were identified as Alternaria alternata.Among the 12 plant extracts(1 mg/mL),the extracts of Salvia tiliifolia and Eupatorium adenophora showed potent antifungal effect on A.alternata,with inhibition rates of 55.19％and 40.76％,respectively.The antifungal effect of capillin was enhanced with the increase of concentration,and the EC50 was be-tween 16.418 and 46.576 μg/mL.The treatment of A.alternata with capillin resulted in the minor distortion of mycelia morphology,the re-duction of dry weight,reducing sugar and total protein content.[Conclusion]The pathogenic bacteria of potato early blight in Huize county,Qujing city is A.alternata.The extracts of S.tiliifolia and E.adenophora have good antifungal effects on A.alternata.capillin affects the nor-mal growth of hyphae by hindering the material synthesis and energy metabolism of hyphal cells to achieve a better antifungal effect against A.alternata.
Potato early blightPathogen identificationPlant extractsCapillinAntifungal activity
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