Nitric oxide (NO), a signaling molecule, participates in defense responses during plant–pathogen interactions. S-Nitrosoglutathione (GSNO) is found to be an active intracellular NO storage center and regulated by S-nitrosoglutathione reductase (GSNOR) in plants. However, the role of GSNOR in NO-induced disease resistance is not clear. In this research, the effects of NO and GSNOR inhibitor (N6022) on the defense response of harvested peach fruit to Monilinia fructicola infection were investigated. It was found that the disease incidence and lesion diameter of peach fruits were markedly (P < 0.05) reduced by NO and GSNOR inhibitor. However, the expression of GSNOR was significantly inhibited (P < 0.05) by NO only during 2–6 h. Analyses using iodo-TMT tags to detect the nitrosylation sites of GSNOR revealed that the sulfhydryl group of the 85-cysteine site was nitrosylated after NO treatment in peach fruit at 6 and 12 h, suggesting that exogenous NO enhances disease resistance via initial inhibition of gene expression and the S-nitrosylation of GSNOR, thereby inhibiting GSNOR activity. Moreover, NO and GSNOR inhibitor enhanced the expression of systemic acquired resistance (SAR)-related genes, such as pathogenesis-related gene 1 (PR1), nonexpressor of PR1 (NPR1), and TGACG-binding factor 1 (TGA1). These results demonstrated that S-nitrosylation of GSNOR protein and inhibition of GSNOR activity contributed to the enhanced disease resistance in fruit.

In this paper, the microstructure, water properties and browning control of Chinese water chestnut (CWC) after harvest were studied. Results showed that the tuber cell contained a large number of starch granules (5-10 μm for each one). The water-holding capacity of tuber cell was weak and T2 relaxation time was 28.5-75.6 ms. Sucrose was the main sugar component in Chinese water chestnut, which account for 84.8% of total sugar. In addition, potassium sorbate, green tea polyphenol and chitosan decreased the browning of fresh-cut CWC compared with the other anti-browning agents such as acetic acid, citric acid, oxalic acid, vitamin C and thyme oil. Moreover, chitosan coating combined with potassium sorbate and green tea polyphenol delayed weight loss and decay of fresh-cut tubers, also maintained a higher soluble solids and ascorbic acid content. The study provided an alternative method for controlling CWC browning, which would be helpful for the application of anti-browning agents in CWC processing.

In order to investigate the controlled release and antifungal effect of thyme essential oil on peach fruit, the four polysaccharides such as xanthan gum, gum tragacanth, arabic gum and pullulan were used to construct the essential oil-chitosan based composite film. The physical and chemical properties of composite film and its inhibition effect on Monilinia fructicola of peach fruit in vitro and in vivo were evaluated. The results showed that thyme essential oil contained some antifungal compounds such as 2-methoxy-3- (2-propenyl)-phenol, D-limonene and thymol. The addition of four polysaccharides decreased the tensile strength and elongation at break of composite film, and caused obvious fluctuation in the peak at 3263, 2884, 1552 and 1025 cm-1. Particularly, the strong interaction was found between chitosan and arabic gum which improved the antifungal effect of thyme essential oil in vitro. Moreover, the chitosan composite film combined with arabic gum exhibited the best inhibition effect on Monilinia fructicola of peach fruit in vivo regardless of the coating of film solution or film fumigation method. The work showed that chitosan-arabic gum composite film would be a potential application for improving the antifungal effect of essential oil on the preservation of peach fruit.