Increased activity of MdFRK2, a high-affinity fructokinase, leads to upregulation of sorbitol metabolism and downregulation of sucrose metabolism in apple leaves.

ABSTRACT: To investigate the functions of fructokinase (FRK) in apple (Malus domestica) carbohydrate metabolism, we cloned the coding sequences of MdFRK1 and MdFRK2 from the 'Royal Gala' apple. The results showed that MdFRK2 expression was extremely high in shoot tips and young fruit. Analyses of heterologously expressed proteins revealed that MdFRK2 had a higher affinity for fructose than did MdFRK1, with Km values of 0.1 and 0.62 mM for MdFRK2 and MdFRK1, respectively. The two proteins, however, exhibited similar Vmax values when their activities were significantly inhibited by high concentrations of fructose. MdFRK2 ectopic expression was associated with a general decrease in fructose concentration in transgenic lines. In leaves, increased FRK activity similarly

SUBMITTER: Yang J 

PROVIDER: S-EPMC6269498 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature