Population dynamics of Rhodotorula mucilaginosa on apples, apple defense response, and transcriptomic response of the yeast to patulin

Rhodotorula mucilaginosa, is an antagonistic yeast that has the ability to inhibit postharvest diseases of apples and effectively degrade patulin. The present study was designed to investigate the population dynamics of the yeast on the surface of apple fruit, the induction of defense response in apple, and the transcriptomic response of R. mucilaginosa to patulin. Results demonstrated that the population of R. mucilaginosa remained stable on the surface of apples kept at either 20 degrees C or 4 degrees C. Furthermore, R. mucilaginosa increased the activity of defense-related enzymes in apples, including chitinase and beta-1,3-glucanase, which presumably enhanced the disease resistance of apples. The RNA-Seq analysis, identified 182 differentially expressed genes (DEGs), which included 104 that were up-regulated and 78 that were down-regulated genes. Further analysis indicated that the degradation of patulin by R. mucilaginosa was highly regulated, and identified the major stress tolerance-related DEGs and metabolic pathways involved in patulin degradation.