材料，对其块根中的可溶性糖（蔗糖、葡萄糖和果糖）和淀粉含量以及4种蔗糖分解酶的活性进行测定与相关性分析，以明确调控甘薯块根中可溶性糖和淀粉含量的关键蔗糖分解酶种类。结果表明：（1）明确甘薯块根中活性最高的蔗糖分解酶为蔗糖合成酶（Sus），其次为细胞质转化酶（CIN）和液泡转化酶（VIN），细胞壁转化酶（CWIN）的活性最低。（2）本研究表明，除了已报道的VIN外，CIN活性也和己糖含量之间呈显著正相关，高己糖含量的甘薯品种块根中具有更高的VIN和CIN活性;（3）甘薯块根中Sus活性和淀粉含量之间呈极显著正相关，高淀粉甘薯品种具有更高的Sus活性;（4）CWIN活性非常低，其在块根发育中的具体作用有待进一步深入研究。总之，蔗糖分解酶对甘薯品质有重要影响，其中Sus是调控甘薯块根淀粉含量的关键酶类，而CIN和VIN是调控块根中己糖含量的关键酶类。
关键词 甘薯;转化酶;蔗糖合成酶;淀粉;己糖中图分类号 S531 文献标识码 A
Differential Roles of Four Sucrose-degrading Enzymes in the Formation of Qualities of the Storage Roots of Sweet Potato
ZHAN Leilei， ZHU Guopeng*， LIU Yonghua*
College of Horticulture， Hainan University， Haikou， Hainan 570228， China
Abstract The study was aimed to identify the sucrose-degrading enzymes playing key regulatory roles in the quality formation of sweet potato and the content of carbohydrates （i.e. sucrose， glucose， fructose and starch） in the storage roots of two sweet potato cultivars. The cultivars had large differences in carbohydrate content and enzyme activities. Sucrose synthase （Sus） activity was the highest among the four sucrose-degrading enzymes， followed by cytoplasmic invertase （CIN） and vacuolar invertase （VIN）. Cell wall invertase （CWIN） activity was the lowest. Besides VIN， it was found for the first time that there was also a significant positive correlation between CIN activity and hexose content. Cultivar with higher hexose content also had a higher CIN and VIN activity. There was a positive correlation between Sus activity and starch content. CWIN activity was the lowest among the four sucrose-degrading enzymes and its function in quality formation of storage root remained to be elucidated. Sus maight play key regulatory roles in starch accumulation of storage roots， whereas VIN and CIN play key regulatory roles in hexose accumulation.
Keywords sweet potato; invertase; sucrose synthase; starch; hexose
DOI 10.3969/j.issn.1000-2561.2019.09.008
甘薯（Ipomoea batatas Lam.）又名紅薯、地瓜等，在世界范围内均有广泛栽培，是全球第七大农作物[1]。甘薯高产、耐瘠薄且营养丰富，不仅是重要的粮食作物[2]，还是重要的工业原料、饲料、新型能源及保健作物[3]。中国是世界上主要的甘薯生产国，2014年中国甘薯的栽培面积和产量分别占全球的42%和68%（FAO，2015），稳居世界第一。随着人们生活水平的不断提高，我国甘薯消费结构正在向饲料比例减少、鲜食和食品加工比例增加的方向发展，人们对甘薯品质的要求越来越高[4]。其中，淀粉和可溶性糖含量是影响鲜食型甘薯品质的重要因素。
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