Abstract:

【Objective】 To analyze expression profiles of ethylene receptors during fruit ripening and storage at chilling temperature, and investigate the relationship between expressions of ethylene receptors and chilling tolerance induced by heat pre-treatment (38℃ for 3 days). 【Method】 Using the PCR degenerate primers designed with reference to the conserved amino acid sequences of known ETR, total RNA extracted from banana peel tissues was used as templates, then ETR cDNA fragments were amplified by RT-PCR. Their expression characteristics were studied by the Northern hybridization. 【Result】 The results showed that different expression patterns of two ethylene receptor genes in the banana peel and pulp were observed. Ma-ETR1 expression gradually weakened during fruit ripening while Ma-ERS3 expression accumulated slightly at the later stage of fruit ripening, but the expression of Ma-ETR1 was inhibited. However, the expression of Ma-ERS3 was enhanced by exogenous propylene treatment and high temperature, respectively, in both the peel and pulp tissues. Chilling temperature induced the expression of Ma-ETR1 in the peel and Ma-ERS3 in the pulp, but the accumulation of Ma-ETR1 in the peel tissue induced by chilling temperature was blocked by a heat pre-treatment. 【Conclusion】 These results indicate that the expression of Ma-ERS3 is positively regulated while the expression of Ma-ETR1 is negatively regulated by ethylene or high temperature treatment. Moreover, the inhibition of the accumulation of Ma-ETR1 in the peel tissues induced by chilling temperature is related to the chilling tolerance of harvested banana fruit induced by heat pretreatment.

Key words: banana, ethylene receptor, cDNA cloning, gene expression, ripening, chilling tolerance