Identification of Rice Seed-Derived Fusarium spp. and Development of LAMP Assay against Fusarium fujikuroi

Fusarium species are important seedborne pathogens that cause rice bakanae disease (RBD). In this study, 421 strains were isolated from 25 rice samples collected from Zhejiang, Anhui, and Jiangxi provinces of China. Furthermore, 407 isolates were identified as F. fujikuroi (80.05% isolation frequency), F. proliferatum (8.31%), F. equiseti (5.94%), F. incarnatum (2.61%), F. andiyazi (0.95%), and F. asiaticum (0.48%) based on morphology and translation elongation factor 1-alpha (TEF1-α) gene. Phylogenetic analysis of combined sequences of the RNA polymerase II largest subunit (RPB1), RNA polymerase II second largest subunit (RPB2), TEF1-α gene, and ribosomal DNA (rDNA) internal transcribed spacer (ITS) showed that 17 representative strains were attributed to six species. Pathogenicity tests showed that representative isolates possessed varying ability to cause symptoms of bakanae on rice seedlings. Moreover, the seed germination assay revealed that six isolates had different effects, such as inhibition of seed germination, as well as seed and bud rot. The loop mediated isothermal amplification (LAMP)-based assay were developed for the detection of F. fujikuroi. According to sequences of desaturase-coding gene promoter, a species-specific marker desM231 was developed for the detection of F. fujikuroi. The LAMP assay using seeds collected from field was validated, and diagnostics developed are efficient, rapid, and sensitive.