Proton exchange in the nitrate vacuolar transporter AtCLCa is required for growth and nitrogen use efficiency

Hodin, J.; Lind, C.; Marmagne, A.; Espagne, C.; Bianchi, M. W.; De Angeli, A.; Abou Choucha, F.; Bourge, M.; Chardon, F.; Thomine, S.; Filleur, S.

doi:10.1101/2022.09.21.508937

bioRxiv · 10.1101/2022.09.21.508937

Proton exchange in the nitrate vacuolar transporter AtCLCa is required for growth and nitrogen use efficiency

Hodin, J.·Lind, C.·Marmagne, A.·Espagne, C.·Bianchi, M. W.·De Angeli, A.·Abou Choucha, F.·Bourge, M.·Chardon, F.·Thomine, S.·Filleur, S.

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Abstract

Nitrate is a major nutrient and osmoticum for plants. To deal with its fluctuating availability in soils, plants store it into vacuoles. AtCLCa, a 2NO3-/1H+ exchanger localized on the vacuole ensures this storage process. It belongs to the CLC family that includes exchangers and channels. A mutation in a glutamate residue conserved across CLC exchangers is likely responsible for the conversion of exchangers to channels. Here, we show that a clca mutant of this residue, E203, behaves as an anion channel in its native membrane. To investigate its physiological importance, we introduced the AtCLCaE203Apoint mutation in a clca KO mutant. We first showed that these AtCLCaE203A mutants display a growth deficit linked to water homeostasis disruption. Additionally, AtCLCaE203Aexpression is not able to complement the clca defect in nitrate accumulation and favors higher N-assimilation at the vegetative stage. Further analyses at post-flowering stages indicated that AtCLCaE203A results in an increase of N uptake allocation to seeds, leading to a higher nitrogen use efficiency compared to wild-type. Altogether, these results point out the critical function of the AtCLCa exchanger on the vacuole for plant metabolism and development.

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Hodin, J., Lind, C., Marmagne, A., Espagne, C., Bianchi, M. W., De Angeli, A., Abou Choucha, F., Bourge, M., Chardon, F., Thomine, S., Filleur, S.. 2022-09-22. Proton exchange in the nitrate vacuolar transporter AtCLCa is required for growth and nitrogen use efficiency. https://doi.org/10.1101/2022.09.21.508937

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