Effect of ethylene and 1-MCP on post-harvest physiology and on expression of the ethylene receptor genes PpETR3 and PpERS2 in pear (Pyrus pyrifolia Nakai 'Kikusui') fruit

Exogenous ethylene and 1-MCP were investigated for their potential effects on fruit quality, post-harvest physiology, and expression of the ethylene receptor genes PpETR3 and PpERS2 in 'Kikusui' pear fruit. The results Showed that exogenous ethylene treatment promoted a reduction in fruit firmness and soluble solids content (SSC), an increase in the activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) at a later stage of fruit storage, improved the rates of respiration and ethylene release, and up-regulated expression of the PpERS2 gene from 0-9 d after harvest, but did not affect expression of PpETR3. However, the effects of 1-MCP on fruit quality and post-harvest physiology were contrary to those of ethylene. 1-MCP up-regulated expression of the PpETR3 gene from 0-9 d and down-regulated expression of PpERS2 from 6-15 d after harvest. These data indicate that exogenous ethylene or 1-MCP could accelerate or inhibit pear fruit ripening during storage, respectively. At different stages of storage, ethylene and 1-MCP had different effects on the expression of PpETR3 and PpERS2. Moreover, the expression patterns of PpETR3 and PpERS2 during fruit ripening suggest that these two ethylene receptors have important functions during ethylene signal transduction.