title: Characterisation of genes encoding key enzymes involved in sugar metabolism of apple fruit in controlled atmosphere storage.
abstract: Sugars are essential contributors to fruit flavour. Controlled atmosphere (CA) storage has been proved to be beneficial for maintaining harvested fruit quality. To explore regulatory mechanism of sugar metabolism in fruit stored in CA condition, we cloned several genes, encoding key enzymes, involved in sugar metabolism in apple fruit, and analyzed sugar contents, along with gene expression and enzyme activities in fruits stored in air and CA. The results indicated that CA could maintain higher contents of sugars, including sucrose, fructose and glucose. Expression levels of key genes, such as sucrose synthase (SS), sucrose phosphate synthase (SPS), fructokinase (FK) and hexokinase (HK), were shown to be correlated with the corresponding enzyme activities. We found that activities of neutral invertase (NI), vacuolar invertase (VI), FK and HK were inhibited, but SPS activity was promoted in apple fruit stored in CA, suggesting that CA storage could enhance sucrose synthesis and delay hydrolysis of sucrose and hexose. These findings provided molecular evidence to explain why higher sugar levels in harvested fruit are maintained under CA storage.
authors.affiliation: Key Laboratory of Plant Resources, Institute of Botany, The Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Zhu
authors.initials: Z
authors.lastname: Zhu
authors.forename: Ruiling
authors.initials: R
authors.lastname: Liu
authors.forename: Boqiang
authors.initials: B
authors.lastname: Li
authors.forename: Shiping
authors.initials: S
authors.lastname: Tian
mesh_terms: D003001:Cloning, Molecular; D004187:Disaccharides / Q000378:metabolism*; D061353:Food Storage; D005638:Fruit / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism; D027845:Malus / Q000737:chemistry / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D009005:Monosaccharides / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D043324:beta-Fructofuranosidase / Q000235:genetics / Q000378:metabolism
chemical_list: D004187:Disaccharides; D009005:Monosaccharides; D010940:Plant Proteins; D005964:Glucosyltransferases; C022699:sucrose synthase; C022698:sucrose-phosphate synthase; D043324:beta-Fructofuranosidase
keywords: Apple fruit; Controlled atmosphere; Key genes; Sugar metabolism