Influence of drop shock on physiological responses and genes expression of apple fruit

The aim of our study was to investigate the effect of drop shock on physiological responses and genes expression in harvested apple fruit stored at 20 +/- 2 degrees C. Ethylene production, respiratory rate, firmness, soluble solid content, relative electrical conductivity, LOX (lipoxygenase) activity, MDA (malondialdehyde) content, variation of volatile compounds, ethylene biosynthetic genes, and ethylene receptor genes of apple fruit were examined. The results indicated that drop shock observably resulted in the increase of ethylene production, respiratory rate, soluble solid content, relative electrical conductivity, LOX activity, MDA content and gene expression levels in apples. Furthermore, drop shock significantly decreased firmness and high-intensitive drop shock stimulated the accumulation of aldehydes and esters in harvested apples. Overall, the greater impact on apple quality is the effect of larger amplitude of shock during truck transportation, which seriously reduced storage life and quality of postharvest apples.