1-MCP effects in nectarines: dependence on storage temperature, and relationship with polyamines.

1-Methylcyclopropene (1-MCP) inhibits ethylene action and fruit quality achievement by binding to ethylene receptors. Developmental stage, timing, concentration and storage temperature may modulate 1-MCP effects. Ethylene and the antisenescent growth regulators polyamines (PAs) share a common precursor and may exert opposite effects. Nectarines (Prunus persica L. Batsch \u2018Stark Red Gold\u2019) were harvested and treated with 1-MCP for 12 h at 25\ub0C, and then stored for 3 days at 25 or 4\ub0C. At 25\ub0C, 1-MCP strongly inhibited ethylene production and Pp-ACO gene expression, and development of quality parameters (softening, SSC, loss of acidity). At 4\ub0C, ethylene production was not inhibited, but enhanced on the third day. A transient increase in endogenous PAs is associated with 1-MCP treatment, which at 4\ub0C is accentuated, suggesting a combined negative effect of 1-MCP and cold stress. In fact, the 1-MCP-induced increase in PA levels seems to be more correlated with the cold stress than with preventing post-harvest ripening. Thus, in nectarines a single dose of 1-MCP is sufficient to improve post-harvest storage at 25\ub0C, but has a less beneficial effect at 4\ub0C