As the physiology of the fruit changes during maturation and senescence,the inhibitors of fungal growth decreased and the fruit became more susceptible to postharvest pathogens,especially to necrotrophic ones.Biocontrol yeast Rhodosporidium paludigenum was found to be effective when activating inducible resistance responses in fruit tissues,and proved superior due to its additional biological control effects.However,information on the mechanisms by which antagonists suppress the diseases beyond the inhibition is still incomplete.In the present study,the microarray data mining revealed that R.paludigenum activated transcription of genes important for plant hormones,signaling transduction,stress and defensive responses in orange peel tissue.Moreover,up-regulation of phenylalanine andtyrosine metabolism,phenylpropanoids biosynthesis,and alkaloid biosynthesis I,were observed at the transcription level.Conversely,large amounts of genes involved in starch metabolism,oligosaccharide and glycoside metabolism were markedly repressed by R.paludigenum treatment.Activation of phenylpropanoids biosynthesis pathway was correlated with the increasing production of phenolic acids and their subsequent metabolite lignin,indicating antifungal metabolites indeed contributed to biocontrol yeast enhanced fruit protection.Blocking ethylene perception with 1-MCP resulted in an increase in ACS1,ACS2 and ACO expression,and consequently an increase in ethylene production during mechanical wounding and resistance induction.When applied at concentrations greater than 500 ppb 1-MCP pre-fumigation significantly reduced the fruits natural protection and R.paludigenum induced disease resistances to P.digitatum decay,indicating that ethylene perception was involved in disease resistance induction.Moreover,the expression of the yeast upregulated defensive genes CHI,β-1,3-glucanase,PAL and CIN that were inhibited to different degrees by the 1-MCP pre-treatment in the Ponkan mandarin.