Multi-gene identification and pathogenicity analysis of sugarcane pokkah boeng in Yunnan Province

Abstract Sugarcane pokkah boeng disease is a fungal disease caused by Fusarium oxysporum. Eighty-seven samples of sugarcane pokkah boeng disease were isolated from Kaiyuan, Jinggu, Menglian, Yongde and Zhenkang sugarcane districts in Yunnan, and PCR amplification of the isolated Fusarium species was carried out by utilizing the sequences of the TEF, RPB2 and TUB2genes, and the results showed clear and bright bands consistent with the size of the target bands. The products were sequenced and analyzed by BLAST on NCBI website, and the sequences of strains with high homology were obtained to construct a phylogenetic tree with them. Combined with field symptom diagnosis, molecular characterization and morphological observation, five pathogenic bacteria causing sugarcane pokkah boeng were identified, namely Fusarium incarnatum、Fusarium andiyazi、Fusarium sacchari、Fusariumproliferatum and Fusarium verticillioides. F. incarnatum、 F. andiyazi and F. sacchari are reported for the first time in Yunnan sugarcane area. The mycelial morphology and conidial size of the five pathogenic bacteria did not differ much, and it was difficult to identify the causal agent of sugarcane tip rot by the difference in conidial size. The results of pathogenicity analysis by isolated inoculation showed that all five pathogens were able to infect and cause Sugarcane pokkah boengsymptoms in sugarcane, among which F. proliferatum was the most pathogenic, and the length and expansion of the spots were significantly higher than the others; on the contrary, F. verticillioides was the weakest pathogen. This study further clarified the types of F. verticillioides pathogens and their pathogenicity in Yunnan cane area, which provides scientific basis for the prevention and control of sugarcane pokkah boeng.