Community Research and Development Information Service - CORDIS

Final Activity Report Summary - NODPERCEPTION (An integrated, interdisciplinary approach to Nod factor perception)

Legume plants such as peas, beans, soybeans, clover and lucerne are able to form a symbiosis with soil bacteria called rhizobia, which leads to the development of nodules on the roots of the plants in which the bacteria fix atmospheric dinitrogen. By using the fixed nitrogen, legumes can grow without nitrogen fertilisers and produce protein rich food and feed. Because of these reasons, legumes will play an increasing role in sustainable agricultural systems. In order for the legume and the rhizobia to recognise each other they use chemical signalling, involving lipochitooligosaccharidic Nod factors. These molecules are produced by the bacterium and perceived by the legume and lead to the infection and development of the root nodules. Nod factors are currently used in agriculture for improving legume yield.

The Research Training Network NODPERCEPTION has employed a multidisciplinary approach to understand the molecular mechanisms of Nod factor perception using the model legume plant Medicago truncatula, which is closely related to lucerne and pea. The project has united eight research groups in Toulouse, Grenoble, Szeged, Amsterdam, Wageningen, Warsaw, Madrid and Norwich, from six European countries (France, Hungary, the Netherlands, Poland, Spain and the United Kingdom). These groups involve chemists and biologists, either expert in the symbiosis or in techniques used to study lipochitooligosaccharides and their interactions with protein receptors. During the project fourteen Early Stage Researchers and four Experienced Researchers were recruited on contracts of between 3 to 36 months. These researchers each had specific research projects which involved collaboration with other groups in the network leading to an integrated approach to studying Nod factor perception.

By synthesising Nod factors analogues and using spectroscopic and computational approaches, the network showed that the lipid part of the Nod factor is highly flexible and can adopt different structures, which partially determine the Nod factor biological activity. Studies on the legume protein receptors, their interacting proteins and Nod factor responses suggest that the plant uses at least two perception and calcium signalling mechanisms to regulate nodulation and to ensure that infection occurs only with the bacterium with the correct Nod factor signal. These results suggest a close co-evolution of the legume and its rhizobial symbiont to respectively produce and respond to Nod factors, allowing the development of this beneficial plant-microbe interaction.

The results suggest that Nod factor perception and signalling is a highly complex and regulated process which requires further investigation in order to optimise the use of Nod factors and rhizobia for crop improvement. During this project the recruited researchers used a variety of techniques, including chemoenzymatic synthesis, plant transformation, fluorescence microscopy, nuclear magnetic resonance and molecular modelling to address the biological question. They became familiar with the language and techniques used in the complementary disciplines. Coupled with training in scientific presentations, scientific writing and career development, the network has contributed to the goal of producing a mobile, knowledgeable workforce, able to contribute to modern, interdisciplinary research and related professions.

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