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Heat treatments and expansin gene expression in strawberry fruit

Dotto, Marcela C., Pombo, Marina A., Martínez, Gustavo A., Civello, Pedro M.
Scientia horticulturae 2011 v.130 no.4 pp. 775-780
air, cell walls, disinfestation, ethylene production, firmness, fruits, gene expression, genes, heat treatment, ovens, postharvest technology, protein synthesis, ripening, strawberries, stress response
Heat treatments have been applied in fruit postharvest technology for insect disinfestations, decay control, ripening delay and modification of fruit responses to other stresses. Heat treatment affects several aspects of fruit ripening, such as ethylene production and cell wall degradation probably through changes in gene expression and protein synthesis. In this paper, strawberries (Fragaria×ananassa Duch., cv Camarosa) at 50–75% red stage of ripening were heat-treated at 45°C during 3h in an air oven and then stored at 20°C for 0, 4, 18, 24 and 48h. Fruit firmness was determined and the expression of a set of expansin genes (FaEXP1, FaEXP2, FaEXP4, FaEXP5 and FaEXP6) was analyzed. The firmness of treated fruit was higher than that of control fruit 24h after treatment, though the differences disappeared after 48h at 20°C. The analysis by northern-blot indicated that heat treatments affected differently the expression of expansin genes. The expression of FaEXP1, FaEXP2 and FaEXP6 was lower in treated fruit during the following 24h post-treatment. The lower expression of these expansin genes could contribute to delay softening after heat treatment.