Hutton Highlights, May 2020

20 Hutton Highlights Nodulation is a process through which legume plants form a symbiosis with bacteria that live in the roots of the plants and take nitrogen from the atmosphere to convert it into compounds that the plant can use for its growth. In cereal crops like maize, wheat and barley, there is no capacity for making these root nodules, and so these crops are dependent on farmers applying large quantities of fertiliser to obtain their nitrogen. Fertilisers are very expensive and are now recognised as highly damaging in terms of pollution from nitrates going into drinking water, as well as producing very high greenhouse gas emissions that contribute to global warming. A major aim in biotechnology is to try and transfer the root nodulating ability of legumes to cereal crops so that they are no longer dependent on expensive and polluting nitrate fertilisers. The Hutton-supported Engineering Nitrogen Symbiosis for Africa (ENSA) research project is specifically targeting maize as an important crop in sub-Saharan Africa for smallholder farmers who cannot afford fertiliser. However, the transfer of nodulation ability to maize is very complicated, as several genes are involved. “The Amazon is one of the world’s highest biodiversity regions and is home to many legume species, which makes it a prime site for sampling root nodules. The expedition focussed on an area of Brazil around the Rio Cuieiras, a tributary of the Rio Negro, during a period of increased precipitation and meltwaters from the Andes, resulting in many of the forests being flooded” Euan explains. “We’re trying to build up a pattern of how nodulation evolved in these more primitive and mainly tree relatives of the advanced crops peas and beans in order to see how we might engineer a simple symbiosis into maize. “This expedition was quite an experience and I would like to acknowledge the invaluable support and assistance of the Instituto Nacional de Pesquisas Amazônicas (INPA), especially Dr Charles Zartmann, without whom it would not have been possible. Huge thanks must also go to Dr Domingos Cardoso (UFBA, Salvador, BA) and Dr Haroldo de Lima (Jardim Botanico, Rio de Janeiro, RJ) for their botanical expertise, and Dr Eduardo Gross (UESC, Ilheus, BA) for his help. The assistance and hospitality of communities in the Rio Cuieiras are also acknowledged.” Funded by the Bill & Melinda Gates Foundation and led by the Sainsbury Laboratory, ENSA research partners are Aarhus University, University of Cambridge, University of Freiburg, University of Illinois, John Innes Centre, NIAB, University of Toulouse III, Wageningen University & Research and the James Hutton Institute. Visit www.ensa.ac.uk for more information. Exploring legume nodulation in the deepest reaches of the Amazon An international effort to develop maize crops that don’t need fertiliser has taken Hutton scientist Euan James to the deepest reaches of the Amazon River, on a quest for samples of root nodules from legume trees to help understand how these plants were able to develop the ability to obtain their own nitrogen from soil – and whether this trait can be transferred to other crops.