Molecular identification and pathogenicity analysis of bacterial sheath rot pathogen in different types of banana

Objective Banana (Musa spp.) is an important ecomomic crop in South China, banana bacterial sheath rot disease has been found in recent years, which severely affects banana production. This study aimed to clarify the pathogens from different types of bananas and their pathogenicity differentiation.

Method The pathogens of bacterial sheath rot were isolated from different types of bananas, and were identified by PCR using Dickeya genus-specific primers. The pathogens were further confirmed by analyzing the nucleotide sequence similarity of 16S rDNA, constructing the phylogenetic analysis based on six housekeeping genes (fusA, gyrA, recA, gyrB, dnaJ, and dnaX), and analyzing the collinear relationship. The pathogenicity of isolated pathogens were analyzed by in vitro and in vivo inoculating pseudostems and seedlings of banana.

Result Fifteen strains were isolated from different types of bananas and identified as Dickeya spp. by PCR. All fifteen strains were confirmed as D. dadantii according to the results of 16S rDNA nucleotide sequences analysis, the phylogenetic analysis based on the six housekeeping genes and the collinearity analysis. The pathogenicity analysis showed that the pathogenicity of fifteen strains could be classified into three types, the strong pathogenic strains included XJ1, XJ8, XJ12 and control XJ5-1, the relatively strong pathogenic strains included XJ2, XJ3, XJ4, XJ7 and XJ11, and the moderate pathogenic strains included XJ5, XJ6, XJ9, XJ10 and XJ13.

Conclusion All the pathogens causing bacterial sheath rot from different types of bananas belong to D. dadantii, yet there is obvious pathogenic differentiation among them, which provides a basis for future research on the pathogenic mechanisms of D. dadantii and the prevention and control of banana bacterial sheath rot.