Summary Priming of defence is a strategy employed by plants exposed to stress to enhance resistance against future stress episodes with minimal associated costs on growth. Here, we test the hypothesis that application of priming agents to seeds can result in plants with primed defences. We measured resistance to arthropod herbivores and disease in tomato (Solanum lycopersicum) plants grown from seed treated with jasmonic acid (JA) and/or β‐aminobutryric acid (BABA). Plants grown from JA‐treated seed showed increased resistance against herbivory by spider mites, caterpillars and aphids, and against the necrotrophic fungal pathogen, Botrytis cinerea. BABA seed treatment provided primed defence against powdery mildew disease caused by the biotrophic fungal pathogen, Oidium neolycopersici. Priming responses were long‐lasting, with significant increases in resistance sustained in plants grown from treated seed for at least 8 wk, and were associated with enhanced defence gene expression during pathogen attack. There was no significant antagonism between different forms of defence in plants grown from seeds treated with a combination of JA and BABA. Long‐term defence priming by seed treatments was not accompanied by reductions in growth, and may therefore be suitable for commercial exploitation.

The effect of continuous exposure to ozone on quality changes during the storage of red bell peppers, cucumbers and zucchini was investigated. Peppers were stored at 14 °C and were exposed to ozone at 0.1 and 0.3 µmol mol -1 , while cucumbers and zucchini were stored at 12 and 8 °C, respectively and exposed to ozone at 0.1 µmol mol -1 . The content of fructose (2.75 g/100 g FW) and glucose (2.00 g/100 g FW) in red bell peppers exposed to ozone at 0.1 µmol mol -1 was increased by 8 and 7%, respectively when compared to controls. Continuous exposure to ozone at 0.3 µmol mol -1 , on the other hand, had no effect on fructose (2.52 g/100 g FW) and glucose (1.88 g/100 g FW) content. The content of vitamin C was significantly enhanced in red bell peppers exposed to ozone at 0.1 and 0.3 µmol mol -1 after 7 days of storage, however, this effect was not maintained. After 14 days, vitamin C content in peppers exposed to ozone at 0.1 µmol mol -1 was not significantly different from the control, whereas it was reduced at 0.3 µmol mol -1 . Total phenolics content was increased in peppers exposed to ozone at 0.1 µmol mol -1 , but was unaffected at 0.3 µmol mol -1 . Continuous exposure of red bell peppers to ozone at 0.1 and 0.3 µmol mol -1 had no significant effect on weight loss, texture and colour. In cucumbers and zucchini, continuous exposure to ozone at 0.1 µmol mol -1 reduced weight loss by more than 40% and improved texture maintenance, while having no significant effect on their biochemistry. The findings from this study suggest that continuous exposure to ozone at 0.1 µmol mol -1 is a promising method for shelf-life extension of cucumbers and zucchini. Even though in red bell peppers continuously exposed to ozone at 0.1 µmol mol -1 sugars and phenolics content was increased, further work is still needed to better understand the exact mechanism of ozone action and its potential for the industrial use.

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The effect of continuous exposure to ozone at 0.45, 0.9 and 2 μmol mol -1 on quality changes during the storage of red and green chilli peppers at 10 °C was investigated. Ozone at 0.45 and 0.9 μmol mol -1 reduced disease incidence in red peppers, with no further benefits at 2 μmol mol -1 . Ozone at 0.9 μmol mol -1 reduced weight loss during storage and improved firmness maintenance. Skin colour was bleached in red peppers exposed to ozone at 2 μmol mol -1 , and in green ones at all tested doses. Total phenolic content was not affected by ozone but antioxidant activity was reduced in green chilli peppers exposed to ozone at 2 μmol mol -1 , due to lower ascorbic acid content in those samples. Ozone at 0.9 μmol mol -1 extended the shelf-life of chilli peppers.

BACKGROUND Quality management in the fresh produce industry is an important issue. Spinach is exposed to various adverse conditions (temperature, light, etc.) within the supply chain. The present experiments were conducted to investigate the effect of light conditions (dark, low‐intensity light (LL) and high‐intensity light (HL)) and photoperiod (6 h HL and 18 h dark) on the quality changes of cold‐stored spinach. RESULTS HL exposure resulted in oxidative stress, causing tissue damage and quality loss as evidenced by increased membrane damage and water loss. The content of total ascorbic acid was reduced under HL conditions. On the other hand, storage of spinach under LL conditions gave promising results, as nutritional quality was not reduced, while texture maintenance was improved. No significant differences, with the exception of nutritional quality, were found between spinach leaves stored under continuous (24 h) low‐intensity light (30–35 µmol m−2 s−1) and their counterparts stored under the same light integral over 6 h (130–140 µmol m−2 s−1). CONCLUSION LL extended the shelf‐life of spinach. The amount of light received by the leaves was the key factor affecting produce quality. Light intensity, however, has to be low enough not to cause excess oxidative stress and lead to accelerated senescence. © 2014 Society of Chemical Industry

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The fresh produce industry is constantly growing, due to increasing consumer demand. The shelf-life of some fruit, however, is relatively short, limited by microbial contamination or visual, textural and nutritional quality loss. Thus, techniques for reducing undesired microbial contamination, spoilage and decay, as well as maintaining product's visual, textural and nutritional quality are in high demand at all steps within the supply chain. The postharvest use of signalling molecules, i.e. jasmonates and salicylates seems to have unexplored potential. The focus of this review is on the effects of treatment with jasmonates and salicylates on the fresh produce quality, defined by decay incidence and severity, chilling injury, maintenance of texture, visual quality, taste and aroma, and nutritional content. Postharvest treatments with jasmonates and salicylates have the ability to reduce decay by increasing fruit resistance to diseases and reducing chilling injury in numerous products.These treatments also possess the ability to improve other quality characteristics, i.e. appearance, texture maintenance and nutritional content. Furthermore, they can easily be combined with other treatments, e.g. heat treatment, ultrasound treatment. A good understanding of all the benefits and limitations related to the postharvest use of jasmonates and salicylates is needed, and relevant information has been reviewed in this paper.

Highlights • Thyme oil exposure led to up-regulation of PAL gene expression in Hass and Ryan fruit. • Thyme oil exposure led to down-regulation of LOX gene expression in both cultivars.