Zhang Muqing, Zhuo Xiaolei, Wang Jihua, Yang Chuanyu, Powell Charles A, Chen Rukai
State Key Laboratory of Conservation and Utilization of Subtropical Agri-Biological Resources, Guangxi University, Nanning, 530005 China ; Fujian Agricultural and Forestry University, Fuzhou, 350002 China.
Fujian Agricultural and Forestry University, Fuzhou, 350002 China.
Mol Breed. 2015;35(3):100. doi: 10.1007/s11032-015-0295-4. Epub 2015 Mar 15.
Sugarcane is one of the most important crops cultivated for the production of sugar and ethanol. In our previous studies, an innovative positive selection system for obtaining transgenic sugarcane, which utilized the -derived gene as the selectable marker and mannose as the selective agent, was developed and patented in China. In this paper, the influence of phosphomannose isomerase (PMI) overexpression on the key enzymes of both glycolysis and sucrose metabolism was investigated in transgenic sugarcane through the gene. Overexpressed PMI increased hexokinase activity by approximately 24 % compared with non-transgenic control plants, but pyruvate kinase (PK) activity was reduced by approximately 14 %. In comparison with the non-transgenic control plants, the activities of sucrose synthase, sucrose-phosphate synthase, and acid invertase were also modestly affected in the PMI-overexpressing transgenic plants, but no significant differences were observed at the stalk elongation and maturity stages. However, agronomic and technical traits were not affected by gene overexpression in the transgenic sugarcane. In conclusion, PMI overexpression significantly affected the hexokinase and PK activities by catalyzing the reversible interconversion between mannose-6-phosphate and fructose-6-phosphate, which is an intermediate of glycolysis. However, it had no significant effects on sucrose accumulation in sugarcane.
甘蔗是用于生产糖和乙醇的最重要作物之一。在我们之前的研究中，开发了一种用于获得转基因甘蔗的创新正向选择系统，该系统利用源自的基因作为选择标记，以甘露糖作为选择剂，并在中国获得了专利。本文通过该基因研究了转基因甘蔗中磷酸甘露糖异构酶（PMI）过表达对糖酵解和蔗糖代谢关键酶的影响。与非转基因对照植物相比，过表达的PMI使己糖激酶活性提高了约24%，但丙酮酸激酶（PK）活性降低了约14%。与非转基因对照植物相比，在过表达PMI的转基因植物中，蔗糖合酶、蔗糖磷酸合酶和酸性转化酶的活性也受到了一定程度的影响，但在茎伸长和成熟阶段未观察到显著差异。然而，转基因甘蔗的农艺和技术性状不受该基因过表达的影响。总之，PMI过表达通过催化甘露糖-6-磷酸和果糖-6-磷酸（糖酵解的中间产物）之间的可逆相互转化，显著影响了己糖激酶和PK的活性。然而，它对甘蔗中蔗糖的积累没有显著影响。
