Analysis Of Physiological And Biochemical Characteristics And Protein Expressions In Internodes Of Sugarcane With Different Cold Resistance Under Low Temperature

Exploring the physiological and biochemical changes of plants under low temperature stress and its mechanism of cold tolerance, to improve crops cold resistance and increase the production of cash crops, has a very important theoretical and practical significance. Seasonal cold current and severe cold weather in recent years had greatly affected the production of sugarcane which caused the sugarcane cold cultivar selection and the cold resistant mechanism research received the enormous attention. Two sugarcane varieties GT28(cold resistant) and ROC22(cold susceptible) were studied by means of artificial temperature-controlled phytotron, and the changes of soluble protein content, SOD activity, POD activity, Mg2+-ATPase activity in sugarcane internodes were investigated under low temperature. The differential expressions of proteins in internodes of different sugarcane varieties were also analyzed using two dimensional electrophoresis technique. The main results were as follows:1. The soluble protein content changes in different parts of ROC22were basically the same which first increased and then decreased, but there were still some differences. The soluble protein content in the upper and middle stems of GT28firstly decreased and then increased, and the lower stem showed a gradual upward trend.2. The SOD and POD activities of GT28were significantly higher than ROC22. The SOD activity in the upper stem of GT28risen first then dropped, and the other parts declined with the extension of the low temperature treatment; The SOD activity in various parts of ROC22increased and then decreased with the stress time. Compared with the control, the SOD activities between the two varieties had achieved a significant difference level. The POD activity of GT28increased and then decreased in the different parts of stem; The POD activity of ROC22decreased then increased in the upper and lower stem but the mid-stem risen first and then decreased.3. The low temperature stress caused the soluble Mg2+-ATPase activity in internodes of sugarcane decreased, and the Mg2+-ATPase activity of GT28with strong cold resistance was higher than ROC22which had a weak cold resistance.4. The SDS-PAGE analysis results showed that the changes of protein bands of the two varieties with differences in cold hardiness were not alike. The amount of protein bands of GT28were increased after low temperature treatment, the molecular weight of the new protein bands induced synthetic were65.6,54.1,51.8,16.6KDa. The amount of protein bands of GT28were reduced with low temperature stress, which both reduced by5bands at5day and11day treatments.5.2-D electrophoresis patterns for total proteins in the internodes of GT28and ROC22were affected by low temperature stress, there were some differences between two sugarcane varieties. Most of the changed proteins concentrated in low molecular weight area, and the proteins of high molecular weight area kept stable. Down-regulated proteins of GT28were less than ROC22, but up-regulated proteins and special expressing proteins of GT28were more than ROC22, the changes of these proteins were closely related to cold hardiness which suggested that the changes of internodes proteins expression of GT28might be the important physiological reasons for its strong tolerance to low temperature stress.