Fungi genetics contributing to food security

Ian Sanders uses natural genetic variations in fungi to increase cassava production in tropical countries. (Félix Imhof © UNIL)

Mélanie Affentrager / L’Uniscope
As a result of his work on the genetics of microscopic fungi, Ian Sanders has tripled production of cassava in Columbia.

An innate curiosity for plants, animals and life forms, inherited from his mother who was a science teacher, lie at the root of what followed. ‘Even as a child, I was a naturalist at heart,’ confides Ian Sanders, Professor in the Department of Ecology and Evolution (Faculty of Biology and Medicine). For almost than thirty years, the British academic has studied plants and the way they interact with minute fungi known as ‘mycorrhizas’. These microorganisms are capable of extending their filaments to carry phosphate present in the soil to plants and thereby promote plant growth. This symbiosis also benefits the fungi, which draw all the resources necessary for their survival – mainly sugars – from their partner.

The power of genetics…

‘Our research demonstrated firstly that certain strains of mycorrhizal fungi increase plant growth, which underlines the importance of microbial biodiversity. We quickly realised that these results could potentially prove extremely useful for increasing agricultural yields,’ recalls the botanical expert. Quietly and calmly, Ian Sanders details the research conducted in his laboratories at UNIL in flawless French, learned at school from age six and delivered with just a hint of an elegant English accent. ‘In concrete terms, we have developed a system that allows the creation in vitro of new strains of fungi that are genetically different. No external gene is introduced. It is a natural technique similar to that used by farmers and agronomists when they cross plant varieties to create new ones.’

…from Latin America…

Since 2011, large-scale field trials have taken place in Colombia in collaboration with Professor Alia Rodriguez Villate of the National University of Colombia in Bogotá. As Ian Sanders further explains, ‘The soils in tropical zones are very acidic. Plants therefore struggle to absorb phosphate and have even greater need of fungi to ensure their growth.’

The researchers decided to test the effects of the microorganism on cassava, as this root is the daily foodstuff of a billion people – a seventh of the world’s population. ‘The Food and Agriculture Organization of the United Nations is promoting cultivation of this plant in developing countries as, contrary to cereals, it is not that sensitive to climatic fluctuations. Its production remains stable from one year to the next.’

While talking, Ian Sanders picks up a transparent plastic sachet lying on his desk. Inside is a fine beige powder. ‘Spores of fungi which we cultivate are mixed with this very light clay. All that is required is to add 0.4 grams to each cassava plant when it is placed in the ground. The supplementary strain mixes with the naturally occurring community of fungi already present on the roots. Thanks to this new method, cassava production in Colombia has tripled, believe it or not’ explains the scientist, for whom studying biology was always the natural option. What is it about this discipline that he likes? The answer is the infinite diversity of nature, which he has always loved getting to grips with by working towards a specific goal.

‘I received my first camera when I was 10 years old. It was an enormous, horribly heavy Soviet Zenith,’ he recalls. Today he combines photography with his travels and research, but with other aspects too, as is evident from the radiant portraits of his two children hanging behind his desk. ‘My 12-year-old son is exactly as I was at his age. He loves nature, remote places.’

…to Africa

In the light of the promising results obtained in Latin America, the Swiss National Science Foundation (SNF) granted 800,000 Swiss francs to establish the project in sub-Saharan Africa. Swiss and Colombian teams now have links to the International Institute of Tropical Agriculture in Kenya and to the Lake Zone Agricultural Research and Development Institute in Tanzania. ‘The climate, soils and varieties of cassava used in these regions are different. At this stage, we do not yet know if the fungi will increase productivity of the plant.’ The first results will be available in spring 2017.

At the same time, Ian Sanders’ team is pursuing research into the genetics of the two partners involved in the process of symbiosis. ‘We are trying to identify the variations in the genome of the fungi that then modify gene expression in the cassava and increase or diminish its productivity.’ This molecular biology research also receives 800,000 Swiss francs in funding from SNF.

To feed the planet

Professor Sanders takes pleasure in recalling that in the 1960s and 70s botanical research contributed a great deal to resolving the problems of famine. He reckons that ‘The cross-breeding of plants and selection of the most productive and disease-resistant plant strains will have saved almost a billion lives.’ It is a method which is reaching its limits today, but which underlines the importance of microbial biodiversity.

‘Forecasts indicate that there will be nine billion of us human beings in 2050. In order to feed the world, I think it is our responsibility, as plant biology researchers, to explore new techniques that will increase plant productivity to ensure long-term food security.’ As the results obtained for Colombian cassava show, applying genetic knowledge now represents a highly promising way forward.

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