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The effect of chitosan (0.1 mol/L) combined with sodium silicate (100 mmol/L) treatment on Alternaria rot caused by Alternaria alternata in postharvest jujube fruit (Ziziphus jujuba Mill. cv. Dongzao) was studied. The results showed that chitosan combined with sodium silicate treatment significantly reduced the lesion diameter, decay incidence, red index and weight loss of jujube fruit compared with control samples. Combining treatment increased the ascorbic acid, flavonoids, total phenolic compounds and lignin content. The level of superoxide anion (O2·-) and hydrogen peroxide of treated samples was also increased compared with the control samples. Meanwhile, the activities of phenylalanine ammonia lyase, polyphenol oxidase, superoxide dismutase, peroxidase, chitinase and β‐1,3‐glucanase were also accumulated in treated jujube samples, while the activity of catalase markedly decreased. These results indicated that chitosan combined with sodium silicate treatment could induce the disease resistance of postharvest jujube. Therefore, coating postharvest jujube using chitosan combined with sodium silicate could promise as a novel method for preventing the disease infection of postharvest jujube. [ABSTRACT FROM AUTHOR]

Abstract: The effect of carbon monoxide (CO) on enzymatic browning of fresh-cut lotus root slices in relation to phenolic metabolism was investigated. Fresh-cut lotus root slices were fumigated with CO gas at 75, 125, 175 or 225 μL/L for 10, 20, 30 or 40 min, and then stored for 8 days at 5 °C. Changes in color, total phenol, malonaldehyde (MDA), and activities of phenolic-associated enzymes including polyphenol oxidase (PPO), peroxidase (POD) and phenylalanine ammonialyase (PAL) in lotus root slices were measured. The results indicated that fumigating fresh-cut lotus root slices with 175 μL/L of CO for 20 min delayed browning and inhibited increase of MDA. Besides, total phenol also showed higher level from 0 to 4 days. Furthermore, the activities of PPO and POD were inhibited, but PAL activity was increased. The present data suggests that CO has the potential to inhibit browning and maintain quality of fresh-cut lotus root slices. [Copyright &y& Elsevier]

• Postharvest CO treatment effectively controlled Alternaria rot in jujube. • CO did not show any antifungal activity to A. alternata in vitro. • CO treatment enhanced the accumulation of antifungal substances. • CO activated disease resistance-related enzymes (PAL, PPO, CHI and GLU) in jujube. CO is a gas signal molecule involved in various physiological and metabolic regulation processes in plants. In the present study, we evaluated the effects of CO fumigation on the control of Alternaria rot in jujube fruit and explored the mechanism of action. Results showed that CO at 10 μmol L−1 significantly reduced lesion diameter in the fruit inoculated with A. alternata without showing any antifungal activity in vitro. CO treatment enhanced the activities of four representative resistance-related enzymes (phenylalanine ammonia-lyase, polyphenol oxidase, chitinase, and β-1,3-glucanase). Furthermore, CO also led to increase in the content of phenolics, flavonoids, lignin, and H 2 O 2. These results indicate that CO induces resistance to Alternaria rot primarily by activating disease resistance-related enzymes and enhancing accumulation of antifungal substances, and that CO can be a promising elicitor of plant defense responses to resist Alternaria rot in postharvest jujube fruit. [ABSTRACT FROM AUTHOR]