Methyl jasmonate primes defense responses against wounding stress and enhances phenolic accumulation in fresh-cut pitaya fruit

The effect of a pre-cutting methyl jasmonate (MeJA) treatment on wound-induced phenolic accumulation in fresh-cut pitaya fruit and the possible mechanisms were investigated. Results showed that MeJA treatment before cutting significantly enhanced the accumulation of the main individual phenolic compounds and improved the antioxidant activity in fresh-cut pitaya fruit. It is evident that MeJA pretreatment induced a priming mechanism in pitaya fruit, since the MeJA treated intact fruit without subsequent wounding stress did not show any significant physiological responses. However, pitaya fruit pretreated with MeJA and followed by cutting showed an augmented capacity to enhance defense responses against wounding stress. These enhanced responses included reactive oxygen species (ROS) burst, increased gene expression and activity of key enzymes involved in phenylpropanoid pathway and ROS scavenging. These results demonstrated that MeJA treatment can effectively enhance the wound-induced accumulation of phenolic compounds and improve the antioxidant activity in fresh-cut pitaya fruit through priming of defense responses against wounding stress.