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Cold induced changes on sugar contents and respiratory enzyme activities in coffee genotypes
(Universidade Federal de Santa Maria, 2010-04) Partelli, Fábio Luiz; Vieira, Henrique Duarte; Rodrigues, Ana Paula Dias; Pais, Isabel; Campostrini, Eliemar; Chaves, Maria Manuela Coelho Cabral; Ramalho, José Cochicho
The present research aimed to characterize some biochemical responses of Coffea canephora (clones 02 and 153) and C. arabica (Catucaí IPR 102) genotypes subjected to low positive temperatures, helping to elucidate the mechanisms involved in cold tolerance. For that, one year old plants were subjected successively to 1) a temperature decrease (0.5oC a day) from 25/20oC to 13/8oC (acclimation period), 2) a three day chilling cycle (3x13/4oC) and to 3) a recovery period of 14 days (25/20oC). In Catucaí (less cold sensitive when compared to clone 02) there was an increased activity in the respiratory enzymes malate dehydrogenase and pyruvate kinase. Furthermore, Catucaí showed significant increases along the cold imposition and the higher absolute values after chilling exposure of the soluble sugars (sucrose, glucose, fructose, raffinose, arabinose and mannitol) that are frequently involved in osmoregulation and membrane stabilization/protection. The analysis of respiratory enzymes and of soluble sugar balance may give valuable information about the cold acclimation/ tolerance mechanisms, contributing to a correct selection and breeding of Coffea sp. genotypes.