Induction of fruit tolerance to chilling injury: physiological and biochemical aspects / Indução de tolerância de frutos às injúrias de frio: aspectos fisiológicos e bioquímicos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2010

RESUMO

Experiments were performed with the purpose to investigate physiological and biochemical responses associated to induction of fruit tolerance to chilling injury and the involvement of ethylene and antioxidant defense system in this process. Nanicão banana and Tahiti lime fruit were submitted to treatments to stimulate or to inhibit ethylene action and heat treatments. In the first and the third experiments, the fruit were conditioned at 37°C for 10 hours or hot water dipped at 45°C for 15 minutes or 53°C for 2 minutes before storage at 1°C (lime) or 6°C (banana). In the second experiment, Tahiti lime fruit were immersed in solutions containing 1.0mM methyl jasmonate or 1.0mM methyl salicylate or treated with 1000nL L-1 1-MCP, before storage at 1°C (control). In the fourth experiment, banana fruit were treated or not (control) with 1000nL L-1 1-MCP before storage at 6°C. The temperature and exposition time of fruit to heat treatments influences the free radical generation and accumulation in the tissues, causing differential induction of chilling tolerance. The fruit exposure to moderate heat treatments decreased the tissue sensitivity to ethylene, maintained membrane stability and resulting in the lower chilling injury index at the end of storage in both fruit. Nevertheless, it was clear that in the case of banana fruit, the heat-induced tolerance is temporary, and is restricted to few days after the cold exposure. The pre storage conditioning of fruit at 37°C for 10 hours trigger a severe stress, since it increased the generation of reactive oxygen species in the tissues favoring the earlier development of chilling injury symptoms in both fruit. There was a considerable increase in the activity of antioxidant enzymes in the flavedo of lime fruit treated with 1.0mM methyl jasmonate or 1.0mM methyl salicylate and this elevation on capacity to scavenge the reactive oxygen species was accompanied by significant decrease in the chilling injury incidence when compared to control fruit. In addition, in lime fruit, the ethylene perception inhibitor 1-MCP did not suppress the ethylene evolution during storage period; consequently, this residual ethylene did reduce the flavedo tissue capacity to scavenge hydrogen peroxide. On the contrary, the ethylene perception inhibition and the suppression of synthesis evolution during storage of banana fruit reduce the sensitivity of fruit to chilling injuries. The combination between low temperature and ethylene favors the oxidative stress, given that did decrease the capacity to scavenge the reactive oxygen species, which induces membrane deterioration events. In conclusion, the treatment effectiveness to induce cold tolerance to fruit was related not only to oxidative stress but also to other factors as ethylene in the tissue. Probably, the interaction of these factors with low temperature may be determinant in the modulation of response required to promote high or low chilling tolerance.

ASSUNTO(S)

banana fruit oxidative stress reguladores vegetais. reactive oxygen species estresse oxidativo enzimas danos por fatores ambientais bioquímica vegetal banana fisiologia vegetal ethylene antioxidantes lima antioxidant enzymes tahiti lime fruit.

ACESSO AO ARTIGO

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