A novel interaction between nitric oxide and ozone controls kiwifruit ripering
Recent data suggest that nitric oxide (NO) acts as a senescence-delaying molecule by downregulating ethylene emission in fruits. Kiwifruit (Actinidia deliciosa) is a climacteric fruit sensitive to ethylene and responds positively to post-harvest ozone application. In the present study, kiwifruit of cv. 'Hayward' were treated pre- and post-harvest with 100 f.lMSNP (a NO donor), then cold-stored (0 °C, R.H. 95%) for 4 months in the absence or presence of ozone (0.3 f.lLL-1 ), and subsequently left to ripen for 15 d at room temperature (20°C, shelf-life). Physiological data showed that the combination of NO and ozone treatments promotes the senescence of kiwifruits and shortens its postharvest shelf-life. Also, NO content and DAF- 2DA fluorescence were modulated in kiwifruits by the treatments applied. Fruits that were pre- and post-harvest treated with SNP, followed by ozone exposure, displayed high levels of ethylene production. The expression of several transcription factors encoding EIN3-Like (ElLs) and Ethylene Response Factors (ERFs) was modulated in fruits exposed to various shelf-life conditions. Using a proteomic approach, several S-nitrosylated and nitrated kiwi proteins were identified during shelf-life ripening, which are mainly involved in energy, protein metabolism, defence and cell structure. These data suggest that the interaction between NO and ozone stimulates kiwifruit ripening.