GRF-mediated regulation of a membrane protein, IRT1, involved in metal uptake

forthcoming

Iron (Fe) is one of the most common metals in the Earth's crust, but plants are often unable to absorb it as it forms insoluble complexes, especially in alkaline soils. This unavailability leads to poor crop yields and low nutritional quality. As Fe fertilization is rather ineffective and costly, around half of the world's crops suffer from iron deficiency. To mitigate Fe deficiency symptoms and maintain nutrient homeostasis, plants rely on a protein called Iron-Regulated Transporter 1 (IRT1) to take up iron from the soil. However, IRT1 also absorbs other metals that are more easily available in Fe-deficient soils. These metals can be harmful to plants if absorbed in excess, causing damage to cellular compounds through the formation of reactive oxygen species. To limit this toxicity, IRT1 is able to sense metal excess, leading to its degradation to avoid further uptake. To better understand this feedback loop, previous work from the host laboratory uncovered interactants of IRT1 under non-Fe metal excess, including General Regulatory Factors (GRFs) which are known to modulate the functions of their targets by controlling their subcellular localization or cell polarity, preventing their degradation or allowing their interaction with additional partners. The GIFT project aims to uncover how plants balance iron uptake and protect themselves from excess of harmful metals to eventually improve crops development and reach better yields. To this avail, I will (1) investigate the involvement of IRT1-interacting GRFs in plant metal homeostasis through molecular and physiological analyses of plant metal excess responses; (2) decipher the molecular mechanisms governing the association of GRFs to IRT1; (3) and elucidate their putative role in the control of IRT1 subcellular localization and cell polarity. This multidisciplinary research will expand my expertise in plant physiology and cellular biology. It will help me to consolidate my position as an independent researcher.