Study on Identification of Seedborne Fusarium species of Rootstock for Watermelon Grafting and Their Pathogenicity

Two Fusarium isolates were obtained from seed embryo and seed coat of rootstock seeds(cvs.Shenlizhenmu and Futianjiangjunzhenmu) for watermelon grafting,repectively.The two isolates were identified using morphological methods and DNA sequencing analysis.Effects on seed germination and pathogenicity to seedlings of these two Fusarium isolates were also determined.The results showed that the two Fusarium strains were identified to be Fusarium oxysporum.They had significant effect on seed germination,compared to control treatment,which causing reduction of germination energy,percentage germination,germination index and vigor index significantly;they were pathogenic to rootstock seedlings and caused typical wilt symptom on leaves,fulfilled Koch’s postulates.To our knowledge,it’s the first report of seedborne F.oxysporum of rootstock for watermelon grafting can be pathogenic to rootstock seedlings in China.