title: Malate metabolism and adaptation to chilling temperature storage by pretreatment with high CO2 levels in Annona cherimola fruit.
abstract: In this study we focused on the effect of a pretreatment with high (20%) CO2 levels on malic acid metabolism in cherimoya (Annona cherimola Mill) fruit stored at chilling temperature. We analyzed the activity of phosphoenolpyruvate carboxylase (PEPC), malate dehydrogenase (MDH), and the NADP-malic enzyme (NADP-ME), involved in the carboxylation/decarboxylation of malate. Our results show that CO2 treatment, which improves tolerance to prolonged storage at chilling temperature, was closely linked to considerably greater NADP-ME activity. These results, combined with lower PEPC activity, may explain the significantly lower amount of malic acid and titratable acidity quantified in CO2-treated fruit. Moreover, the high cytoplasmic MDH enzyme activity and the strong stimulation of NADP-ME activity exhibited by CO2-treated fruit could be contributing factors in the maintenance of fruit energy metabolism, pH stability, and the promotion of synthesis of defense compounds that prevent or repair damage caused by chilling temperature.
authors.affiliation: Departamento de Ciencia y Tecnología de Productos Vegetales, Instituto del Frío, IF-CSIC, Ciudad Universitaria, 28040-Madrid, Spain.
authors.forename: Roberto
authors.initials: R
authors.lastname: Maldonado
authors.forename: M Teresa
authors.initials: MT
authors.lastname: Sanchez-Ballesta
authors.forename: Rafael
authors.initials: R
authors.lastname: Alique
authors.forename: M Isabel
authors.initials: MI
authors.lastname: Escribano
authors.forename: Carmen
authors.initials: C
authors.lastname: Merodio
mesh_terms: D031041:Annona / Q000378:metabolism*; D002245:Carbon Dioxide / Q000008:administration & dosage*; D019343:Citric Acid / Q000032:analysis; D003080:Cold Temperature; D003653:Decarboxylation; D005638:Fruit / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008291:Malate Dehydrogenase / Q000378:metabolism; D008293:Malates / Q000032:analysis / Q000378:metabolism*
chemical_list: D008293:Malates; D002245:Carbon Dioxide; D019343:Citric Acid; C030298:malic acid; D008291:Malate Dehydrogenase; C031917:malate dehydrogenase (oxaloacetate-decarboxylating) (NADP+)