甜菜氮营养对蔗糖积累转化及有关酶活性的调节

Regulating of Nitrogen to Sucrose Synthesis and Sucrose Degradation and Some Enzymes Activities in Beet

试验表明：甜菜块根中蔗糖合成酶（SS）活性和蔗糖磷酸含成酶（SPS）活性高于叶片，随植株氮营养增加，可溶性蛋白含量增加，SS活性较SPS活性提高得更快些，叶片中转化酶活性与氮素供应量呈显著正相关，导致块根，叶片蔗糖和已糖含量下降，叶片转化酶活性是SS活性的170倍左右，转化酶在蔗糖降解中起关键作用，表明氮营养通过影响蔗糖的合成与降解过程，调节蔗糖的实际积累量。放线菌素D对可溶性蛋白质含量、SS活性和SPS活性均比氯霉素有较强的抑制作用，两种抑制剂对SPS的抑制强于对SS的抑制，核基困对这两种酶的表达起支配作用。随氮素水平提高，叶片硝酸还原酶活性（NRA）和植株可溶性蛋白含量增加，导致块根和叶征的蔗糖和己糖含量下降，叶片NRA随生育阶段的变化规律反映了甜菜不同营养阶段的糖氮代谢特点，在糖分积累期，反应液中NO3－－N浓度对NRA的刺激作用最为显著。

Expriment showed that the activities of sucrose synthean and sucrere phosphate Synthetue were higher in sugarbeet roots than in blade. The soluble prutein content of plants increased and sucrose synthetase activity rose faster than the activity of sucrose phosphate synthetase, but the amount of accumulation of sucrose and hexose in the root and in the blade reduced with the incrase of amount of nitrogen application. The activity of invertase in the blade showed a strong positive correlation with amount of nitrogen application. In blade , the activity of invertase was 170tAnes of the activity of sucrose phosphate synthetase.Actinomyctri D had very higher inhibition to soluble protein content,to the activities of sucrose synthetase and sucrose phocphate synthetase than chloramphenicol; the both inhibtors showed higher inhibitiun tu sucrase phusphate sythetase than sucruse synthetase, the role to the express of the both enzymy was dominited by capyon gene.Since lush growing stage of folight to sugar content accumulating stage. the percentage of nitrogen application. N uptake rate by Per day (mg/plant)showed a strong opitive correlation with amount of nitroge application nitrate reductase activity (NRA) in the blade and soluble protein content in the plants were increased with the amount of nitrogen application increased but the content of sucrese and hexose dropping in the roots and blades.The characteristies of the metabolisms uf nitrogen and sugar in different stage were reflected, which come from the law of the NRA varied with various stage of vegetation growth:significant affects of ultrate in assay medium on the NRA in the blades were observed in the sugar content accumulating stage.