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Ratoon stunt is a very important disease affecting sugar cane that is caused by the bacterium Leifsonia xyli subsp. xyli ( Lxx). We inoculated cuttings of the sugar cane varieties Badila and GT11 with Lxx to investigate the effects of this disease on their growth, physiological characteristics and associated gene differential expression, sampling after 150, 180 and 210 days following treatment. In addition, to further explore the colonization of this bacterium at transcription and translation levels, we designed a number of primers from the sequence of an Lxx-specific gene and performed quantitative real-time PCR ( qRT- PCR) for Lxx18460 to detect accumulation in plants. Total proteins from diseased plants were detected using Western blotting with an Lxx-specific gene monoclonal antibody. The results of this study show that bacterial levels gradually increased with plant growth following inoculation. Specifically, plant height, stalk diameter, single stalk weight and water potential all decreased as a result of ratoon stunt infection, while membrane permeability and amino acid content increased in Lxx-infected plants compared to the control. The expression of PAL, ZFP and NBS- LRR genes all also increased in plants subject to ratoon stunt stress; this result suggests that these genes are involved in sugar cane responses to Lxx infection. [ABSTRACT FROM AUTHOR]

[Objective]The present study was carried out to assess the changes of defense-related enzyme activities in sugarcane under ratoon stunting disease( USD), in order to provide references for illustrating the mechanism of interaction between sugarcane and the bacteria of HSD. [Method]Sugarcane variety of GT11 was selected as the plant materials. Seedcanes were treated at 52 °C for 30 min for pathogen free as a control and inoculated with Leifsonia xyli subsp. Xyli (Lxx) as HSD-infected sugarcane. The healthy and HSD-infected sugarcane was confirmed by PCH and the change of defense-related enzyme activity in sugarcane was analyzed in both treatments. [Result] The activities of CAT, SOD, POD and (GR in stem were lower in HSD-infected treatment than those in control on the 90th day after transplant, while they were higher in treatment on the 180th day after transplant as comparison with the control except the activity of APX which was higher in treatment than this in control during sugarcane growth period. In contrast to stem, the activities of CAT, SOD, APX and GR in treatment was higher on the 90th day and lower on the 180th day as comparison to control, while the activity of POD was higher than that of control from 90 days to 180 days after transplant. [Conclusion]The activities of defense enzymes including CAT, SOD, POD, APX and (GR increase more or less in both sugarcane leaf and stem under HSD stress. However, along with longer stress time, they're higher in stem than those of the control. Leaf showed the contrary tide. [ABSTRACT FROM AUTHOR]