Ação do etileno na expressão do gene MdAF3 e atividade enzimática α-L-arabinofuranosidase em maçã (Malus domestica Borkh.) cv. ‘Gala’ durante o armazenamento refrigerado

Abstract

The ‘Gala’ apples has limited shelf life due to changes in texture of the pulp, which can be observed during the first months of storage. These changes are due to changes mediated by enzymes active in the cell wall and middle lamella of cells. Among these enzymes, the α-L-arabinofuranosidases act in the hydrolysis of pectin side chains, showing its importance in changing the texture of the fruit. Expression and activity of these enzymes, as well as other changes that occur during ripening, have been related to ethylene action, although this relationship is not always clear. Thus, the aim of this work was to study the influence of ethylene on gene expression MdAF3 in a clone ‘Gala’ apple (Baigent). Additionally, evaluate the α-Larabinofuranosidase enzyme activity, and other changes, such as firmness and endogenous synthesis of ethylene in response to treatments with exogenous ethylene and 1-MCP. The levels of MdAF3 transcripts were reduced by applying 1MCP and increased by treatment with ethylene, indicating that this gene is regulated by the hormone. The enzyme activity was lower with 1-MCP, and the pulp firmness remained higher with this treatment. These results indicate that the gene MdAF3 encodes a protein with activity α-L-arabinofuranosidase, and this enzyme participates in the processes that culminate with changes in the pulp texture of apples cv. 'Gala'.Besides, it was found that both enzyme activity and gene transcription were important for the storage of this cultivar, since in this period reached higher levels when compared with the fruit at harvest.