4種蔗糖分解酶在甘薯塊根品質形成中的作用

占雷雷 朱國鵬 劉永華

摘 ?要??本研究以2個在可溶性糖和淀粉含量上存在顯著差異的鮮食型甘薯品種為材料，對其塊根中的可溶性糖（蔗糖、葡萄糖和果糖）和淀粉含量以及4種蔗糖分解酶的活性進行測定與相關性分析，以明確調控甘薯塊根中可溶性糖和淀粉含量的關鍵蔗糖分解酶種類。結果表明：（1）明確甘薯塊根中活性最高的蔗糖分解酶為蔗糖合成酶（Sus），其次為細胞質轉化酶（CIN）和液泡轉化酶（VIN），細胞壁轉化酶（CWIN）的活性最低。（2）本研究表明，除了已報道的VIN外，CIN活性也和己糖含量之間呈顯著正相關，高己糖含量的甘薯品種塊根中具有更高的VIN和CIN活性;（3）甘薯塊根中Sus活性和淀粉含量之間呈極顯著正相關，高淀粉甘薯品種具有更高的Sus活性;（4）CWIN活性非常低，其在塊根發育中的具體作用有待進一步深入研究。總之，蔗糖分解酶對甘薯品質有重要影響，其中Sus是調控甘薯塊根淀粉含量的關鍵酶類，而CIN和VIN是調控塊根中己糖含量的關鍵酶類。

關鍵詞 ?甘薯;轉化酶;蔗糖合成酶;淀粉;己糖中圖分類號??S531??????文獻標識碼??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

DOI10.3969/j.issn.1000-2561.2019.09.008

甘薯（Ipomoea batatasLam.）又名紅薯、地瓜等，在世界范圍內均有廣泛栽培，是全球第七大農作物^[1]。甘薯高產、耐瘠薄且營養豐富，不僅是重要的糧食作物^[2]，還是重要的工業原料、飼料、新型能源及保健作物^[3]。中國是世界上主要的甘薯生產國，2014年中國甘薯的栽培面積和產量分別占全球的42%和68%（FAO，2015），穩居世界第一。隨著人們生活水平的不斷提高，我國甘薯消費結構正在向飼料比例減少、鮮食和食品加工比例增加的方向發展，人們對甘薯品質的要求越來越高^[4]。……