Ethylene production and acc oxidase gene expression during fruit ripening of Coffea arabica L.

Abstract

The phytohormone ethylene is involved in several physiological and developmental processes in higher plants, including ripening of fruits, abscission of organs and tissues, senescence, wound response as well as in other abiotic stresses. The enzyme 1-aminocyclopropane-1-carboxylate oxidase (ACO) catalyzes the last step of ethylene biosynthesis. The production of ethylene and the expression of a Coffea arabica ACO gene during the last stages of fruit maturation were investigated. A rapid increase of ethylene production at the green-yellow stage of fruit ripening, after the end of endosperm formation, and a decrease of ethylene production at the cherry stage indicates a climacteric phase during ripening. An ACC oxidase (Ca-ACO) from coffee fruit cDNA was cloned and characterized using primers previously reported. The cDNA is homologous to previously described ACC oxidase cDNA in Coffea. The nucleotide and amino acid deduced sequences of the clone showed high homology with ACO from climacteric fruits. Northern blots were performed to determine the Ca-ACO transcription pattern from different tissues and from fruits at different ripening stages. Coffee fruits at an early ripening stage (green) showed the lowest level of Ca-ACO transcript accumulation. The transcript levels of Ca-ACO did not change significantly during the later stages, suggesting the presence of post- transcriptional control mechanisms. These results, taken together, strongly suggest a climacteric nature of coffee fruit ripening.

Gene expression and enzymatic activity of pectin methylesterase during fruit development and ripening in Coffea arabica L.

“…Towards the end of coffee fruit maturation, when endosperm development is complete, the final process of ripening is initiated. In climacteric fruits like coffee, a burst of ethylene occurs, followed by an increase in size and a change in color of the pericarp (Pereira et al, 2005). Our results showed an increased of both transcript level and enzymatic activity of PME during ripening (210-300 DAF) concomitant with development of the pericarp (Figures 4 and 5).…”

“…Fruit ripening is also associated with textural alterations, which are dramatic in climacteric fruits such as coffee (Pereira et al, 2005). The major textural changes that cause softening of fruit result from enzyme-mediated alterations in the structure and composition of the cell wall and partial or complete solubilization of cell wall polysaccharides, such as pectins (Prasanna et al, 2007).…”

Regulation of ethylene biosynthesis at the level of 1-aminocyclopropane-1-carboxylate oxidase (ACO) gene

“…Also in Alstroemeria, ethylene synthesis is regulated through ACO gene expression, rather than ACS, at the last stages of development (Wagstaff et al 2005). Different isoforms of ACO gene are also involved in ethylene production during fruit development and ripening as shown in melon (Lasserre et al 1996), tomato (Barry et al 1996), peach (Mathooko et al 2004), Coffea arabica (Pereira et al 2005), Ficus carica (Owino et al 2006), and banana (Choudhury et al 2008a, b).…”

Genetic transformation of coffee

“…The ethylene burst stimulates an increase in respiration, which will provide the necessary energy for such metabolic changes. To control coffee maturation, two of the main genes of the enzymes involved in ethylene biosynthesis have been cloned, namely ACC synthase and ACC oxidase (Neupane et al, 1999;Pereira et al, 2005). Introduction A.F.…”