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For the sixth consecutive year, the French Academy of Sciences invited six young biologists to present their research findings recently published in the best international scientific journals. Gabriel Krouk presented the results of his thesis study, conducted at INRA-Montpellier. In attendance was his research director Alain Gojon, head of the Integration of Nutritional Functions Team (1).
The findings, published in 2010 in Developmental Cell, describe a new and original mechanism in plants by which the protein NRT1.1 senses the presence of nitrate in soil and combines the detection of the nutrient with the hormonal control of plant development.
Making the most of soil nitrate content
Gabriel Krouk’s work focuses on nitrate, a major mineral ion and the main source of nitrogen for plants, present in soil but also often rare. As a result, plant roots grow constantly in search of new areas of nitrate-rich soil. Mr. Krouk’s research demonstrates that this root growth is in no way random: on the contrary it is carefully guided by molecular mechanisms that detect the presence and availability of nitrate in the soil.
Gabriel Krouk studied one of these molecular mechanisms using the model plant Arabidopsis thaliana. This specific detection mechanism involves the protein NRT1.1, which has the unique characteristic of being both a membrane transporter which enables the entry of nitrate in the root cells, and a nitrate sensor that can stimulate the growth of roots in areas where this ion is present.
This protein plays a unique role in transporting a plant growth hormone, auxin. When nitrate is abundant in the environment, NRT1.1 directs auxin transport so that the hormone accumulates in the roots, thus accelerating their growth.
New perspectives for fertilisers
This research opens new paths towards improvements in plant nutrition and the use of fertilisers in agriculture. Nitrate is one of the main components in these fertilisers, and the amount that is not taken up by crops causes the pollution of ground and surface water. Discovering the mechanisms implemented naturally by plants to optimise their nitrate uptake may therefore be useful in breeding varieties which require less nitrogen (and, therefore, fertiliser) and are more environmentally-friendly.
(1) INRA-CNRS-Montpellier SupAgro-University of Montpellier Joint Research Unit
Find out more:
> The development of plants is guided by nitrate "sensors" in their roots. Press Info item, July 2010
Reference:
Nitrate-Regulated Auxin Transport by NRT1.1 Defines a Mechanism for Nutrient Sensing in Plants. Gabriel Krouk, Benoît Lacombe, Agnieszka Bielach, Francine Perrine-Walker, Katerina Malinska, Emmanuelle Mounier, Klara Hoyerova, Pascal Tillard, Sarah Leon, Karin Ljung et al. Developmental Cell. 2010 June 15;18(6) pp. 927 – 937.
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