16AGRITECHCAT5: Strategies to reduce waste due to greening in potato tubers

In the UK, tuber greening is directly linked to 116,000 tonnes of household potato waste each year with an additional estimated loss of £60m to UK retailers. In field losses due to tuber greening also cost the industry £37 million per annum. Greening is a negative factor in consumer purchases where a 1% increase in sales is worth £3 million per annum to producers. To address this problem this project brings together two academic partners, University of Southampton and James Hutton Institute, who will work together with five industrial partners that span the food chain from production (Branston Ltd), through packaging (Amcor), to major retailers (Tesco and Waitrose). To enable this to happen efficiently the project will be managed by James Hutton Ltd. The project is an early stage proposal designed to elucidate the underpinning scientific knowledge required to develop both short and longer term solutions to this problem.

Based on our understanding of the regulation of chlorophyll synthesis (responsible for greening) in model species, we will uncover the light signalling pathways regulating chlorophyll synthesis in potato tubers and identify the genes that are targets for these signals. The availability of the full potato genome sequence has made it possible to identify the candidate genes involved and expression of these genes will be tested in photobiological experiments using light sources that span the visible spectrum. The reason greening is such a problem is that light also induces the synthesis of glycoalkaloids that are deleterious to human health. We will therefore also characterise the regulation of this pathway. The information from these experiments will directly feed into the development of new, improved packaging materials that target the exclusion of the most effective light wavelengths. It will also provide information that can inform improved storage and in-store lighting regimes. New packaging materials will be tested empirically under laboratory conditions.

In parallel, we will utilise a recently characterised potato mapping population to identify potato lines that show reduced greening. A detailed genetic map for this population and other genomic resources (such as whole-exome capture arrays in which all the expressed genes can be more rapidly analysed) will be deployed within the project. This unprejudiced approach will provide genetic markers for genes associated with reduced greening enabling a longer term strategy to produce new non-greening potato varieties. The markers identified will find application at different screening stages in breeding programmes carried out by consortium members.

In the UK, tuber greening is directly linked to 116,000 tonnes of household potato waste each year with an associated estimated loss of £60m p.a. to UK retailers. In field losses due to tuber greening also cost the industry £37m p.a. Greening is a significantly negative factor in consumer purchases where a 1% increase in sales is worth £3m p.a. to producers. This project brings together partners that span the food chain from production, through packaging, to major supermarkets who will work with academic researchers to develop solutions to reduce tuber greening. Photobiological experiments will identify the conditions and target genes for light-induced tuber greening informing the design of prototype packaging film to reduce greening during storage and in store. Recently developed potato genetic approaches will be used to identify markers for genes associated with reduced greening providing the foundation of a longer term strategy to produce new non-greening potato varieties.

Who might benefit from this research?
This programme has been developed in consultation with a range of UK industrial beneficiaries. Enhanced knowledge and tools relating to potato tuber greening will benefit all sectors of the industry reflecting the involvement of growers and packers, packaging companies and two major retailers. Collectively these beneficiaries have committed significant cash and in-kind funding to the project.
Ultimately the outcomes of this project will impact on sustainable food production and waste reduction. In the UK food self- sufficiency will result in reduced imports and costs to the consumer. In the wider context of a globalised world economy, improved human nutrition anywhere in the world will improve overall global security and thereby have a benefit in the UK.

How might they benefit from this research?
Potato waste is currently estimated to be 40% of the 770,000 tonnes of total household food waste generated by fresh vegetables and salad products in the UK (Fruit and Vegetable Resource Maps, WRAP, June 2011) with 40% of consumers throwing away uncooked potatoes due to greening. Greening also accounts for in-store losses prior to consumer purchase. Tesco estimate that 3% of potatoes go to waste, primarily because of increased greening, at a cost to Tesco of about £12m per year. By extrapolation, this represents a loss of £55-60 million annually across all UK retailers. Reducing the amount of greening will bring people back to purchasing potatoes and increasing sales by just 1% would equate to a £3 million increase in revenue to producers. Moreover, this is not just an issue in the UK as The European Potato Trade Association (http://www.europatat.eu) recently highlighted potato waste as a major issue within the EU industry. Greening also takes place prior to harvest in the field. In field tuber greening costs potato growers £37 million per annum and although the complex trait is due to depth of tuber formation, stolon length and agronomic factors, sensitivity of tubers to light is the most important component. Many of the most popular potato varieties often experience grading losses of up to 15%, due solely to in-field greening. These potatoes are unsuitable for human consumption in any format due to the elevated risk of glycoalkaloids. In 2014 EU Countries imported a total of 6.38Mt of fresh potatoes (excluding seed and starch) with 95% of these from within the EU, but only 2% of these were from the UK. Thus there is a considerable EU export market for UK producers that would be supported by varieties with reduced potential to green.

In this project, the new consortium will employ cutting-edge technologies to develop in depth understanding of the tuber greening process. This will be used to develop both short and long-term approaches to controlling tuber greening. In the short term, understanding of the wavelengths of light that stimulate tuber greening will enable the development of packaging that specifically filters out these wavelengths. We also will use this knowledge to develop new tools for potato breeding using recent advances in potato genomics. Longer term, the route through which almost all genetic advances in crop production must pass to release their benefits to the wider community is the plant breeding sector. The commercial arm of the James Hutton Institute, James Hutton Limited, runs potato breeding programmes for all the major UK potato producers and so we are well placed to translate the outcomes of this research to the potato industry. Improved packaging and markers can both be easily incorporated into the potato production chain. Within the consortium are groups that have the potential to deliver these innovations and a clear route as to how they could be deployed within the potato supply chain.