Penicillium expansum is an important postharvest pome fruit pathogen causing massive spoilage of stored fruits and high economic losses. The present study aimed to identify an essential gene of P. ...expansum and to investigate its effect in postharvest apple infection. Cytoscape and RNA-sequencing analysis identified a P. expansum PeBgl1 gene which was a hub gene and also upregulated expression at three key time points (1, 3, and 6 h) during apple infection. The PeBgl1 gene was 798 bp in length, encoded 265 amino acids and had high homology with glycoside hydrolase superfamily of P. expansum. The PeBgl1 gene affected the colony morphology especially the colony color and delayed fungal growth both of P. expansum both in vivo and in vitro. This gene also decreased the pathogenicity of P. expansum in apples. Based on these results, we conclude that PeBgl1 is responsible for growth and pathogenicity in P. expansum.
•PeBgl1 is identified as an essential gene of P. expansum during apple infection.•PeBgl1 gene knockout delays P. expansum growth and morphology.•PeBgl1 knocked out decreased the pathogenicity of P. expansum in apple.
β-1,3-glucanase plays an important role in the biodegradation, reconstruction, and development of β-1,3-glucan. An endo-β-1,3-glucanase which was encoded by PeBgl1 was expressed, purified and ...characterized from Penicillium expansum for the first time. The PeBgl1 gene was amplified and transformed into the competent cells of E. coli Rosetta strain with the help of the pET-30a cloning vector. The recombinant protein PeBgl1 was expressed successfully at the induction conditions of 0.8 mmol/L IPTG at 16 °C for 16 h and then was purified by nickel ion affinity chromatography. The optimum reaction temperature of PeBgl1 was 55 °C and it had maximal activity at pH 6.0 according to the enzymatic analysis. Nasub.2HPOsub.4-NaHsub.2POsub.4 buffer (pH 6.0) and NaCl have inhibitory and enhancing effects on the enzyme activities, respectively. SDS, TritonX-100 and some metal ions (Mgsup.2+, Casup.2+, Basup.2+, Cusup.2+, and Znsup.2+) have an inhibitory effect on the enzyme activity. The results showed that PeBgl1 protein has good enzyme activity at 50–60 °C and at pH 5.0–9.0, and it is not a metal dependent enzyme, which makes it robust for storage and transportation, ultimately holding great promise in green biotechnology and biorefining.
•The population of R. mucilaginosa kept stable in surfaces of apples.•R. mucilaginosa had the ability to induce defense-related enzymes of apples.•Metabolic and glycolytic process of R. mucilaginosa ...involved in patulin degradation.
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 °C or 4 °C. Furthermore, R. mucilaginosa increased the activity of defense-related enzymes in apples, including chitinase and β-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.
•GABA enhanced biocontrol efficacy of S. pararoseus Y16 to Aspergillus rot of grapes.•GABA induced PPO, POD and PAL activities of grapes treated with S. pararoseus Y16.•GABA increased flavonoids, ...phenolic content of grapes treated with S. pararoseus Y16.•The expression levels of PPO, POD and PAL of grapes were increased.
Aspergillus tubingensis is a fungal pathogen that can cause Aspergillus rot in grapes and produces ochratoxin A. This study investigated the effect of Gamma-aminobutyric acid (GABA) on the biocontrol efficacy of Sporidiobolus pararoseus Y16 against Aspergillus rot in postharvest grapes. The results showed that GABA- treated S. pararoseus Y16 had a better control effect on A. tubingensis in rot rate, rot diameter, spore germination rate, and germ tube length compared with S. pararoseus Y16 alone. After 5 d post-inoculation, the decay rates of control, S. pararoseus Y16 treated, and GABA-treated S. pararoseus Y16 were 100%, 52.78% and 16.67% in grapes, respectively. Moreover, GABA-treated S. pararoseus Y16 had a better growth rate and more stable reproduction than S. pararoseus Y16. In the growth dynamic experiment, GABA-treated S. pararoseus Y16 has a better growth rate and a more stable reproduction than S. pararoseus Y16, under both 4 °C and 20 °C. The GABA-treated S. pararoseus Y16 significantly enhanced grapes’ resistance-related enzyme activities and gene expression. Importantly, GABA-treated S. pararoseus Y16 effectively increased the activities of PPO, POD, PAL and the content of total phenols and flavonoids in grapes. In conclusion, GABA could potentially improve the biocontrol efficiency of S. pararoseus Y16 against Aspergillus rot in grapes via altering the yeast’s physiology and the grape’s disease-resistance system.
•The up-regulated DEPs were associated with the energy metabolism and glucose metabolism.•Oxidative phosphorylation is the highest pathway in metabolism from KEGG enrichments.•Vc treatment induced ...the cell wall and energy synthesis of P. caribbica under oxidative stress.
Ascorbic acid (vitamin C, Vc) is a well-known antioxidant, which can eliminate reactive oxygen species (ROS) in order to protect yeasts subjected oxidative stress. In our previous research, Pichia caribbica, one of the antagonistic yeasts showed an activity against postharvest diseases of apples, and Vc enhanced the tolerance to oxidative stress of P. caribbica, and improved its biocontrol efficacy to postharvest blue mold decay of apples. However, the mechanisms, especially the molecular mechanisms of the tolerance of P. caribbica improved by Vc under oxidative stress are not sufficiently clear. The purpose of this research was to investigate the protein expression profile and transcriptome characterization of P. caribbica induced by Vc under oxidative stress. The proteomics results showed that there were 31 differentially expressed proteins (DEPs), among them 25 DEPs were up-regulated and 6 DEPs were down-regulated. These up-regulated DEPs were associated with the energy metabolism and glucose metabolism, including fructose – bisphosphate aldolase, malate dehydrogenase, peroxisomal catalase and so on. Transcriptomics analysis showed that 68 genes were differentially expressed, among them 38 genes were up-regulated and 30 genes were down-regulated. These up-regulated genes were found to be related to cell wall, energy synthesis, polysaccharides hydrolysis and antioxidant activity.
