Sergeeva E M, Larichev K T, Salina E A, Kochetov A V
Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.
Vavilovskii Zhurnal Genet Selektsii. 2022 May;26(3):250-263. doi: 10.18699/VJGB-22-32.
Starch is a major storage carbohydrate in plants. It is an important source of calories in the human and animal diet. Also, it is widely used in various industries. Native starch consists of water-insoluble semicrystalline granules formed by natural glucose polymers amylose and amylopectin. The physicochemical properties of starch are determined by the amylose:amylopectin ratio in the granule and degrees of their polymerization and phosphorylation. Potato Solanum tuberosum L. is one of the main starch-producing crops. Growing industrial needs necessitate the breeding of plant varieties with increased starch content and specified starch properties. This task demands detailed information on starch metabolism in the producing plant. It is a complex process, requiring the orchestrated work of many enzymes, transporter and targeting proteins, transcription factors, and other regulators. Two types of starch are recognized with regard to their biological functions. Transitory starch is synthesized in chloroplasts of photosynthetic organs and degraded in the absence of light, providing carbohydrates for cell needs. Storage starch is synthesized and stored in amyloplasts of storage organs: grains and tubers. The main enzymatic reactions of starch biosynthesis and degradation, as well as carbohydrate transport and metabolism, are well known in the case of transitory starch of the model plant Arabidopsis thaliana. Less is known about features of starch metabolism in storage organs, in particular, potato tubers. Several issues remain obscure: the roles of enzyme isoforms and different regulatory factors in tissues at various plant developmental stages and under different environmental conditions; alternative enzymatic processes; targeting and transport proteins. In this review, the key enzymatic reactions of plant carbohydrate metabolism, transitory and storage starch biosynthesis, and starch degradation are discussed, and features specific for potato are outlined. Attention is also paid to the known regulatory factors affecting starch metabolism.
淀粉是植物中主要的储存碳水化合物。它是人类和动物饮食中重要的热量来源。此外，它还广泛应用于各种行业。天然淀粉由水不溶性半结晶颗粒组成，这些颗粒由天然葡萄糖聚合物直链淀粉和支链淀粉形成。淀粉的物理化学性质由颗粒中的直链淀粉与支链淀粉比例及其聚合度和磷酸化程度决定。马铃薯（Solanum tuberosum L.）是主要的淀粉生产作物之一。不断增长的工业需求使得培育淀粉含量增加且具有特定淀粉特性的植物品种成为必要。这项任务需要有关淀粉生产植物中淀粉代谢的详细信息。这是一个复杂的过程，需要许多酶、转运蛋白和靶向蛋白、转录因子及其他调节因子协同工作。就其生物学功能而言，淀粉可分为两类。暂存淀粉在光合器官的叶绿体中合成，并在无光条件下降解，为细胞提供碳水化合物。储存淀粉在储存器官（谷物和块茎）的造粉体中合成并储存。在模式植物拟南芥的暂存淀粉方面，淀粉生物合成和降解的主要酶促反应以及碳水化合物的运输和代谢已为人熟知。而关于储存器官，特别是马铃薯块茎中淀粉代谢的特征了解较少。几个问题仍不明确：酶同工型和不同调节因子在植物不同发育阶段及不同环境条件下的组织中的作用；替代酶促过程；靶向和运输蛋白。在这篇综述中，讨论了植物碳水化合物代谢、暂存和储存淀粉生物合成以及淀粉降解的关键酶促反应，并概述了马铃薯特有的特征。同时也关注了影响淀粉代谢的已知调节因子。
