| Abstract:【Objective】In recent years, with the expansion of the cultivation area of flowering Chinese cabbage and the
emergence of repeated cropping, soft rot diseases are increasing year by year, among which soft rot bacterial is one of the main
diseases that harm the yield and quality of flowering Chinese cabbage severely. The study aims to evaluate the resistance of
different varieties of flowering Chinese cabbage to soft rot disease in order to screen disease-resistant varieties.【Method】Samples of flowering Chinese cabbage with typical soft rot symptoms were collected, and the soft rot pathogens were identified
by tissue isolation, morphology and molecular biology methods. Fifty-two different varieties of flowering Chinese cabbage were
used as experimental materials, and the spray inoculation method was used for inoculation during seedling period: two edges
of about 5 mm were lightly scratched on the stem of flowering Chinese cabbage with a blade, and 1×108
CFU/mL bacterial
solution was sprayed onto the wound surface with a small hand-held sprayer. The disease index and soft rot grading were
measured 3 d after the inoculation, and the resistance level of 52 flowering Chinese cabbage varieties was evaluated.【Result】
The isolates were obtained by tissue isolation. The colony morphological characteristics verified by Koch’s rule and 16S rDNA
sequence analysis showed that the strain was a pathogenic bacterium caused by soft rot, and the colonies formed on NA medium
were circular, translucent, milky white, with a central protrusion and smooth edges, which could make the tissues of flowering
Chinese cabbage rotten, and the leaves showed wet rot and wilting symptoms after inoculation in flowering Chinese cabbage
seedlings. Among the 52 materials, There were significant differences in the resistance of most varieties of flowering Chinese
cabbage to soft rot. Among the 52 materials, 35 were highly susceptible, 16 were susceptible, 1 was intermediate resistant, and
no variety showed high resistance or immunization. In general, susceptible varieties accounted for 98.1%. The results showed
that there was a lack of resistant materials among the 52 flowering Chinese cabbage varieties, which may be one of the reasons
for the serious incidence of soft rot in Guangdong Province.【Conclusion】Among the 52 flowering Chinese cabbage varieties,
highly susceptible and susceptible varieties accounted for 98.1%, 1 was intermediate resistant, and no variety showed high
resistance or immunization. The results could provide a scientific basis for the selection and promotion of flowering Chinese
cabbage varieties resistant to soft rot. |
