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Présentation de l'intervention:

The plasticity of plant developmental programs is incredibly complex. The root system is a fantastic model to study plant plasticity as the number and location of lateral roots is highly variable and strongly affected by the local environment. Amongst the numerous stimuli that can affect root architecture, our group focuses on the effect of phosphate (Pi) availability. Not only phosphate is an essential nutrient that is present in fundamental molecules such as ATP, DNA, RNA and phospholipids; it is also characterized by a low mobility in soil. As a result of its adsorption by cations, only a fraction of the total soil phosphate is readily available for uptake by root systems. In order to cope with these limitations, plants have developed strategies to perceive Pi, adapt their development and modify their physiology. At the root level, phosphate starvation triggers a rapid arrest of primary root growth, an induction of lateral root formation and elongation as well as production of numerous and longer root hairs. It has been suggested that modification of auxin fluxes due to primary root growth inhibition was responsible for lateral root induction. In this presentation, I will provide evidence that this is not the case. Using different approaches, I was able to uncouple these two responses. Manipulation of external versus internal Pi concentration and tissue specific complementation of a mutant affected in root responses to low Pi provided the evidence for two distinct sites of Pi perception in roots and allowed to identify the tissue involved in phosphate perception/response.

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