Molecular Detection And Physiological And Biochemical Changes Of Sugarcane Mosaic Disease

The present study was tend to diagnose the viral population which caused sugarcane mosaic disease in the sugarcane growing area of Guangxi. At the same time, different combinations of sugarcane hybrid seeds were collected to study on transmission of Sugarcane mosaic virus, Sorghum mosaic virus and Yellow leaf virus in hybrid seed of sugarcane. To provide a scientific basis for the cultivation of sugarcane resources. The main pathogen of sugarcane mosaic disease in Guangxi was used to study physiological and biochemical changed on three sugarcane varieties with different resistance. At the part of physiological metabolism, sugarcane varieties YT93-159, ROC22 and GT29 were selected, the sugarcane were inoculated by syringe, and the physiological metabolism indexes of sugarcane leaves were investigated after infected with SrMV that confirmation by RT-PCR. The results were as followed:1. The results of viral population of Guangxi sugarcane showed that 33 in 48 samples were detected with SrMV positive,2 samples were SCMV and only 1 sample was co-infected by SCMV and SrMV, no MDMV and JGMV were detected. The rate of infected samples was account for 75.0% of the total samples. The main pathogen was SrMV. In addition, there were symptoms-showed samples failed to detect virus, This meant that other unknown viruses might be existed in Guangxi sugarcane growing area.2. The results showed that only sample H4 was SrMV-positive in 10 samples of sugarcane seeds, but not any viruses could be detected in the seedlings. It suggested that SrMV could be transmitted from sugarcane plant to seeds, but failed seeds to seedlings.3. The results showed that the contents of chlorophyll, plant height, stem diameter and brix of infected sugarcane plant were lower than their control, the first three indicators had no significant difference compared with control, while the chlorophyll content of GT29 and ROC22 have an extremely significant and significant differences in the level of control after inoculation for 45 days. The resistant varieties GT29 and ROC22 were higher than the susceptible variety YT93-159 in these 4 indicators, but not significant. The chlorophyll content in infected plants showed rising volatility process under the healthy control. It suggested that there was a destruction of chloroplasts to gradually restore process in a longer time after infected disease. The contents of soluble sugar of YT93-159 was sharply reduced at a early time after inoculation, while the resistant varieties GT29 and ROC22 got rose, and the highest resistant variety GT29 had the biggest rise. Accordingly, the contents of soluble sugar can be as an index to evaluate the resistance of different varieties sugarcane in 20 days. The contents of soluble protein in YT93-159 was higher than GT29 and ROC22 in both infected plants and healthy control. It meant that the contents of soluble protein was inversely associated with the resistance varieties.After inoculation, the activities of POD and SOD in YT93-159 had the largest declined, but rose up in GT29 and ROC22. On the content of MDA, it was rose up early and fast, but also came down fast in the resistant varieties GT29 and ROC22, while declined at the very start and then maintain a rise state for a long time in YT93-159. Combined with the changed of POD and SOD activity, it could be known that the resistant varieties were more sensitive to the viruses and started the defense system rapidly, reduced membrane lipid oxidation, and then resisted virus stressed. The PPO and PAL activity in different resistance of sugarcane were excited after inoculation. In the susceptible serious period, the PPO activity were higher in the resistant varieties GT29 and ROC22 than YT93-159, and fluctuated significantly in YT93-159. The changed of PAL was different among different varieties. The increase of PAL activity were higher in the YT93-159 compared to GT29 and ROC22 at the beginning, but contrary in later. The resistant varieties GT29 and ROC22 were more stable and lasting than the susceptible variety YT93-159 to against SrMV.