Transcript profiling analysis of Rhodosporidium paludigenum-mediated signalling pathways and defense responses in mandarin orange.

To investigate the basis of inducible resistance response in postharvest mandarin orange, cDNA microarray and high-performance liquid chromatography were performed to study transcriptional and metabolic changes in Rhodosporidium paludigenum strain treated fruit. The microarray data mining revealed that R. paludigenum activated transcription of genes important for plant hormones, signalling transduction, stress and defensive responses in orange peel tissue. Moreover, up-regulation of phenylalanine and tyrosine 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. Our findings provide an important basis for understanding the mechanisms of resistance induction in mandarin orange, as well as for reducing postharvest losses.