Manipulating oxygen-dependent ethylene signalling in fruit to reduce food loss

Reducing food loss and waste is essential to ensure food security and in achieving United Nations Sustainable Development Goal 12.3 and Sainsburys Supermarkets Plc sustainability targets. Controlled atmosphere (CA) is broadly used to delay ripening and senescence. It consists of reducing oxygen concentrations and increasing carbon dioxide levels in the atmosphere surrounding fresh produce during storage (Falagan and Terry 2018). However, the sudden change in the gas environment is perceived as an abiotic stress, negatively affecting quality. Graduated Controlled Atmosphere (GCA) was discovered in 2020 and has been shown to extend the storage life of multiple fresh produce types viz. blueberries, vine tomatoes and cherries. GCA gradually reduces oxygen levels in the storage atmosphere rather than instantaneously applying the final CA conditions. GCA has been shown to increase the storage life of blueberries by 25% compared to control by reducing disease incidence when. GCA blueberries were also 27% firmer than CA-stored fruit after 28 days of cold storage (Falagan et al., 2020). The mechanisms behind the improved effect of GCA vs. standard CA on storage life are not known, but it is hypothesized that GCA influences oxygen-dependent ethylene signalling, even in non-climacteric fruit. The aim of the work is to understand the mechanisms by which GCA works compared to standard CA from two perspectives: i) GCA effect on ethylene sensitivity (via low O2 and high CO2 graduation); and ii) natural disease resistance (via high CO2). This work will develop understanding on the relationship between low oxygen environments and the ethylene biosynthesis and abscisic acid (ABA) pathways in a dynamically changing gaseous environment. It will also study the progression of fungal disease (Botrytis cinerea) through microscopy and quantified by PCR.