Study On Sugar Accumulation Of Different Sweet Sorghum And Correlation Between Sugar Metabolism And Related Enzymes

As an efficient energy crops, sweet sorghum with its high sugar content and easilytransformed has been attract the people. To better understand the correlation between keyenzymes of sucrose metabolism and sugar accumulation mechanism, it is great significance tothe breeding of high sugar content of sweet sorghum varieties and improving the sugar content ofsweet sorghum technology. In this study, fructose, glucose, sucrose and total sugar content of12varieties of sweet sorghum leaves and stems in four major growth period were assayed. Then,correlation between sugar content and sucrose phosphate synthase(SPS)and sucrose synthase(SS)with sugar accumulation were investigated. The main results were as follows:1．In mature stage, sucrose was the main sugar in sweet sorghum.2．The change of sucrose is the main factor to affect the change of total sugar content. Inleaves, there was a significant positive correlation between fructose and glucose (R=0.705, P <0.01); no correlation between fructose and sucrose, a negative correlation between glucose andsucrose (R=-0.338, P <0.05). In stems, there was a significant positive correlation betweenfructose and glucose (R=0.82, P <0.01); no correlation between fructose and sucrose, a positivecorrelation between glucose and sucrose (R=0.341, P<0.05).3．In the most vigorous growth of the jointing stage, the sucrose content is the lowest value inthe whole growth period; in mature stage, sucrose content reached its peak. It is illustrated that inthe early growth period sucrose were mainly used by the decomposition of sweet sorghum sugarfor rapid growth, but in mature stage were used to store.4．In the early growth stage, the difference of related enzymes activity between leaves andstems was small, but in the stage of sugar accumulation the difference was significant and therelated enzymes activities in stems were greater than them in leaves. In late growth stage, thesame parts of the SS enzyme activity is generally higher than that of the SPS enzyme activity.5．In the leaves, there was a significant positive correlation between total sugar and SPS andSS activity (R=0.92, P <0.01, R=0.913, P <0.01). In the stems, there was a significantpositive correlation between total sugar and SPS and SS activity (R=0.981, P <0.01, R=0.987,P <0.01), it is illustrated that SPS and SS are important enzymes of sweet sorghum sugaraccumulation.6．In the leaves, there was a significant positive correlation between sucrose and SPS and SS activity (R=0.973, P <0.01, R=0.977, P <0.01). In the stems, there was a significant positivecorrelation between sucrose and SPS and SS activity (R=0.908, P <0.01, R=0.908, P <0.01),it is illustrated that SPS and SS is the effect enzymes of sweet sorghum sucrose metabolism7．In the mature period, the sucrose content, total sugar content, SPS and SS activity inLiaotian No9was far more than the other varieties of the12sweet sorghum varieties.