Root Rot Pathogen Identification and Resistant Germplasm Screening of Isatis indigotica Fort

HAN Yu; SUN Tianqi; TANG Yuman; XU Lingui; SUN Xiaobo; WANG Lihong; SUI Chun

doi:10.15933/j.cnki.1004-3268.2026.03.012

Abstract：The aim is to clarify the root rot pathogen of Isatis indigotica Fort.in the main producing area and the disease resistance of different germplasms.The inoculation effects of three methods were first compared,including root injection,fungal block inoculation and root irrigation methods.And the concentration of root injection method was optimized.Subsequently,I.indigotica pathogens were isolated by tissue separation method.The pathogenicity of the pathogens was determined by the method of injection.Combined with the morphology and gene sequences of ITS,TEF and Tub,the species were identified.Finally,by using the optimized pathogen inoculation method and the most pathogenic strain isolated,the disease resistance of 58 I.indigotica germplasms collected from different producing areas was measured and evaluated.The results showed that the best identification method for resistance to I.indigotica root rot was root injection inoculation with the conidial concentration of 1×107 cfu/mL.Among 36 samples from Heilongjiang,Shanxi,Henan,Xinjiang and Gansu,a total of 68 fungi were isolated.One strain of XJG39 was selected as the strongest pathogenicity through pathogenicity test.Through morphological observation and molecular biological identification,XJG39 was determined to be Fusarium solani.Through disease-resistance analysis,5 resistant germplasms(8.62%)and 7 lowly resistant germplasms(12.07%)were selected.There were 39 susceptible germplasms and 7 highly susceptible germplasms(accounting for 79.31%).The resistance level of root rot was low for most cultivated germplasms in the main producing area of I.indigotica,which was one of the important reasons for the frequent occurrence of root rot.The five selected germplasms can be used as valuable resources for the subsequent research on resistance breeding and resistance genetics of I.indigotica.