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No limits – the biologists who are changing the rules of plant productivity

Professor Zamir is working out how to increase the yield of tomatoes. Image: Shutterstock/ Kingarion
Professor Zamir is working out how to increase the yield of tomatoes. Image: Shutterstock/ Kingarion

‘I would like to show that when one uses novel concepts or thinks outside the box, there is no limit to yield ... the limit is just in our head,’ according to Professor Dani Zamir from the Hebrew University of Jerusalem in Israel.

He is leading the EU-funded YIELD project, which uses groundbreaking applications of modern genomics to stabilise and increase the yield of processing tomato hybrids, which are used to make ketchup and sauces. With this type of tomato, it is not just the number of tomatoes produced that is important, but also how high in sugar each tomato is.

It’s not genetic modification – the team introduces wild species of tomatoes into the commercial strains, and isolates genes that improve specific traits.

Pressure on global food security is likely to increase in coming decades, with population growth estimated to continue for the rest of this century and beyond. At the same time, there is a growing need to address climate change.

YIELD is one of a group of EU-funded projects which are pushing the boundaries of plant productivity, increasing the output of plants on existing farmland while minimising environmental impact.

So far, the project has tested two hybrid plants against the leading varieties on the market and managed to beat most of them for commercial yields. Each year, new commercial varieties are introduced that tend to improve yields by around 1 % but Prof. Zamir hopes to smash this target.

‘I expect that by the end of the project – and it might take a few years because there is the marketing and the testing – we will be able to pick up the yield by 10 %. That will be a successful project.’

He said the key is getting the right people and thinking creatively, an approach that he likens to that taken in sport. ‘There is no limit to what people can do in sport. They always break the records because we analyse the movements and we improve the movements and we come up with new approaches.

‘One has to think in imaginative ways. If we are able to attract the smartest people on the planet into the field of plant breeding then the sky is the limit.’

Sustainable intensification

It’s all part of a new movement in farming to do more with less, known as sustainable intensification.

‘(Sustainable intensification) is this whole goal we’ve got now of trying to produce similar yields or higher yields from the same area of land without increasing environmental damage,’ said Dr Julia Cooper at the University of Newcastle, UK, who ran the EU-funded NUE-CROPS project.

‘If we are able to attract the smartest people on the planet into the field of plant breeding then the sky is the limit.’

Professor Dani Zamir, Hebrew University of Jerusalem in Israel

NUE-CROPS, which finished earlier this year, looked at how to produce varieties of crops that were particularly efficient at taking up nutrients from the soil and would enable farmers to maintain yields while reducing reliance on fertiliser, thereby protecting the environment.

‘We know that in order to achieve high yields of crops we need to add more nutrients but there is a diminishing return, so every additional kilogram of nutrients that you add, you get less return in terms of yield,’ said Dr Cooper.

‘The high yields we now achieve in crop production are beneficial because they’re feeding the world’s growing population but it’s coming with this decline in efficiency. That means that all of the nutrients that the crops aren’t taking up and using to produce yields are causing damage to the environment.’

If nitrogen is left in the soil after harvest then it can enter the air after being converted into ammonia or nitrous oxide, the most damaging greenhouse gas. It can also pollute the water system.

To tackle this problem, the NUE-CROPS team identified nutrient-use efficient (NUE) varieties of four crops – wheat, maize, oilseed rape and potatoes – by testing residual nitrogen in the soil after harvest and working out how much yield the crops produced for a given level of nitrogen. Potatoes were also tested for efficient phosphorus use.

The researchers also identified molecular markers – biological signposts – that can be used by seed companies to determine whether a new variety of crop is nutrient efficient. Using molecular markers means that breeders only need a small amount of plant material, such as a seed or a seedling, to test a plant for NUE, making this approach significantly quicker and easier than going through a full harvest cycle.

Dr Cooper said the project’s work is important in working towards global food security. ‘It’s feeding into this whole programme of sustainable intensification. In order to achieve that goal we have to be improving our efficiency of nutrient use. It’s not the only thing you have to do but it’s one part of the puzzle.’

Another part of the puzzle may come from breeding plants that can withstand hostile weather conditions.

The DROPS project, led by Dr François Tardieu, director of research at the National Institute for Agricultural Research in Montpellier, France, is investigating how to identify varieties of durum wheat and maize that can maintain their production levels in adverse climatic conditions such as air drought, soil drought and high temperatures.

In order to do this, the DROPS team is researching new ways of measuring characteristics such as growth, roots and leaves to determine which varieties perform well in drought conditions. These measurements can then be used to find associations between drought-withstanding varieties and their genetic basis.

The team will also create a model to stimulate how different combinations of alleles – alternative forms of the same gene – would behave in different parts of Europe under different conditions.

While the project is too short to identify drought-resistant genotypes that can be used directly by breeders, researchers hope their work is a crucial step in the right direction.

‘The main result is new methods for characterising genotypes in drought,’ said Dr Tardieu. ‘The second is genes and alleles that cause the plant to behave differently in different scenarios. And third, the big output is a model that is used by seed companies and the public sector.’

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