Starch Biosynthesis and the Key Enzymes of Root and

th , 2012; revised: Oct. 19 th , 2012; accepted: Oct. 29 th , 2012 Abstract: The tuber and root crops are rich in starch in their storage organs and provide important raw mate- rials not only for food and processed food, but also for modified starches and bioenergy. Starch is composed of two types of molecules, amylose and amylopectin. It can only be produced through biosynthetic pathway, a process that involves multiple enzymes of conserved functions in many crops, such as ADP-glucose phos- phorylase, starch synthases, starch branching enzymes and starch debranching enzymes. Here we review re- cent progresses in biological functions and mechanisms of these key enzymes in starch biosynthesis, includ- ing new identified enzymes such as starch phosphorylase and D-enzyme. Their features in amylose and amy- lopectin biosynthesis of tuber and root crops were also explored. It not only provides important information for identification and functional analysis of key enzymes in starch biosynthesis but also bridges the gap be- tween starch structure and property of tuber and root crops.