Botrytis cinerea infection affects wax composition, content and gene expression in blueberry fruit

Effects of Botrytis cinerea (B. cinerea) conidia infection on fruit defense resistance and cuticular wax in blueberry fruit after harvesting were studied. Results showed that B. cinerea conidia infection aggravated fruit weight loss and softening. Meanwhile, pathogen infection induced fruit defense, including the increase of defense enzymes activities. B. cinerea infection also affected the morphology and composition of cuticular wax and expression levels of wax biosynthesis and transport-related genes. Scanning electron microscopic (SEM) analysis revealed that B. cinerea conidia firstly adhered to the epicuticular wax of fruit and then formed mycelial filament and degraded the wax surrounding mycelium. Meanwhile, B. cinerea infection decreased total wax, alkanes and aldehydes, as well as delayed the accumulation of triterpenoid and esters content, but increased fatty acids content according to the gas chromatography-mass spectrometry (GC-MS) analysis. The down-regulation expression of wax-related genes was delayed. Altogether, these findings suggest that B. cinerea disrupted blueberry cuticular wax layer, stimulated fruit defense enzymes and delayed down-regulation of blueberry wax genes.