Changes in carbohydrate content in zucchini fruit (Cucurbita pepo L.) under low temperature stress.
The postharvest handling of zucchini fruit includes low-temperature storage, making cold stress unavoidable. We have investigated the changes of soluble carbohydrates under this stress and its relation with weight loss and chilling injury in zucchini fruit during postharvest storage at 4 °C and 20 °C for up to 14 days. Two varieties with different degrees of chilling tolerance were compared: Natura, the more tolerant variety, and Sinatra, the variety that suffered more severe chilling-injury symptoms and weight loss. In both varieties, total soluble carbohydrates, reducing soluble carbohydrates and polyols content was generally higher during storage at 4 °C than at 20 °C, thus these parameters are related to the physiological response of zucchini fruit to cold stress. However, the raffinose content increased in Natura and Sinatra fruits during storage at 4 °C and 20 °C, although at 20 °C the increase in raffinose was more remarkable than at 4 °C in both varieties, so that the role of raffinose could be more likely related to dehydration than to chilling susceptibility of zucchini fruit. Glucose, fructose, pinitol, and acid invertase activity registered opposite trends in both varieties against chilling, increasing in Natura and decreasing in Sinatra. The increase in acid invertase activity in Natura fruit during cold storage could contribute in part to the increase of these reducing sugars, whose metabolism could be involved in the adaptation to postharvest cold storage.
Department of Plant Physiology, Facultad de Ciencias, University of Granada, Fuentenueva s/n, 18071 Granada, Spain. Electronic address: fpalma@ugr.es.
Francisco
F
Palma
Department of Plant Physiology, Facultad de Ciencias, University of Granada, Fuentenueva s/n, 18071 Granada, Spain.
Fátima
F
Carvajal
Department of Plant Physiology, Facultad de Ciencias, University of Granada, Fuentenueva s/n, 18071 Granada, Spain.
Carmen
C
Lluch
Department of Applied Biology, Escuela Superior de Ingeniería, University of Almería, La Cañada de San Urbano s/n, 04120 Almería, Spain.
Manuel
M
Jamilena
Department of Plant Physiology, Facultad de Ciencias, University of Granada, Fuentenueva s/n, 18071 Granada, Spain.
Dolores
D
Garrido
D000222:Adaptation, Physiological; D050260:Carbohydrate Metabolism; D003080:Cold Temperature; D028464:Cucurbita / Q000378:metabolism*; D005638:Fruit / Q000378:metabolism*; D005964:Glucosyltransferases / Q000378:metabolism; D013312:Stress, Physiological; D013402:Sugar Alcohols / Q000378:metabolism; D043324:beta-Fructofuranosidase / Q000378:metabolism
D013402:Sugar Alcohols; D005964:Glucosyltransferases; C022699:sucrose synthase; D043324:beta-Fructofuranosidase
Carbohydrate; Low-temperature; Polyols; Postharvest; Raffinose; Zucchini