Articles
EFFECTS OF THE COMBINED APPLICATION OF 1-MCP + LOW O2 ON RIPENING OF APPLE FRUITS
Article number
857_41
Pages
339 – 348
Language
English
Abstract
For the past two years we have been studying the effects of the combined application of 2 ppm 1-MCP + 1.5% O2 on apple (Malus ×domestica Borkh.) fruit ripening at 1°C and 6.5°C. In fruits stored at 6.5°C, the onset of the C2H4 climacteric occurred 10, 55, and 95 days.
For the controls, 1.5% O2, and 2 ppm 1-MCP, respectively, whereas in fruits treated with 1-MCP and kept under 1.5% O2, the onset of the ethylene climacteric did not occur for 200 d, the duration of the experiment.
The retardation of the climacteric rise was attended by a complete suppression of the ACC synthase 1 (ACS1) and ethylene response sensor 1 (ERS1) genes.
The promoters of both genes contain C2H4-responsive elements.
Thus, once ACS1 is induced, it can sustain the auto-catalytic increase in C2H4 evolution.
The dependence of mRNA accumulation in both genes on C2H4 was also demonstrated by treating climacteric fruits with 1.5% O2, 2 ppm 1-MCP, and 2 ppm 1-MCP + low O2. The degree of decrease in C2H4 evolution differed with the treatments, being stronger in the combined 1-MCP + low O2 treatment.
This was reflected in the amounts of the accumulated transcripts.
At present the developmental changes that precede the induction of ACS1 are unknown.
At 1°C, the climacteric rise in C2H4 evolution was also retarded by the combined treatment for 250 days.
However, when the fruits were transferred after 250 d to 18°C, ripening occurred normally, as could be judged by the rise in C2H4 evolution, softening and induction of the expression of C2H4-dependent genes, e.g., polygalacturonase.
The data thus show that apples treated with 1-MCP + 1.5% O2 can be successfully stored at relatively high temperatures.
The expression of the alcohol dehydrogenase (ADH) gene that is induced by 1.5% O2 is not affected by 1-MCP.
For the controls, 1.5% O2, and 2 ppm 1-MCP, respectively, whereas in fruits treated with 1-MCP and kept under 1.5% O2, the onset of the ethylene climacteric did not occur for 200 d, the duration of the experiment.
The retardation of the climacteric rise was attended by a complete suppression of the ACC synthase 1 (ACS1) and ethylene response sensor 1 (ERS1) genes.
The promoters of both genes contain C2H4-responsive elements.
Thus, once ACS1 is induced, it can sustain the auto-catalytic increase in C2H4 evolution.
The dependence of mRNA accumulation in both genes on C2H4 was also demonstrated by treating climacteric fruits with 1.5% O2, 2 ppm 1-MCP, and 2 ppm 1-MCP + low O2. The degree of decrease in C2H4 evolution differed with the treatments, being stronger in the combined 1-MCP + low O2 treatment.
This was reflected in the amounts of the accumulated transcripts.
At present the developmental changes that precede the induction of ACS1 are unknown.
At 1°C, the climacteric rise in C2H4 evolution was also retarded by the combined treatment for 250 days.
However, when the fruits were transferred after 250 d to 18°C, ripening occurred normally, as could be judged by the rise in C2H4 evolution, softening and induction of the expression of C2H4-dependent genes, e.g., polygalacturonase.
The data thus show that apples treated with 1-MCP + 1.5% O2 can be successfully stored at relatively high temperatures.
The expression of the alcohol dehydrogenase (ADH) gene that is induced by 1.5% O2 is not affected by 1-MCP.
Authors
M. Asif, T. Solomos, P. Trivedi
Keywords
ethylene, apple, climacteric, ripening, oxygen
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