A ppGpp-mediated brake on photosynthesis is required for acclimation to nitrogen limitation in Arabidopsis

Shanna Romand (1) , Hela Abdelkefi (1, 2) , Cecile Lecampion (1) , Mohamed Belaroussi (1) , Melanie Dussenne (1) , Brigitte Ksas (3) , Sylvie Citerne (4) , José Caius (5) , Stefano d'Alessandro (1) , Hatem Fakhfakh (2) , Stefano Caffarri (1) , Michel Havaux (3) , Ben Field (1)

1 LGBP - Luminy Génétique et Biophysique des Plantes
2 University of Tunis El Manar
3 PEPSS - Plant Environmental Physiology and Stress Signaling
4 IJPB - Institut Jean-Pierre Bourgin
5 IPS2 (UMR_9213 / UMR_1403) - Institut des Sciences des Plantes de Paris-Saclay

Guanosine pentaphosphate and tetraphosphate (together referred to as ppGpp) are hyperphosphorylated nucleotides found in bacteria and the chloroplasts of plants and algae. In plants and algae artificial ppGpp accumulation can inhibit chloroplast gene expression, and influence photosynthesis, nutrient remobilisation, growth, and immunity. However, it is so far unknown whether ppGpp is required for abiotic stress acclimation in plants. Here, we demonstrate that ppGpp biosynthesis is necessary for acclimation to nitrogen starvation in Arabidopsis. We show that ppGpp is required for remodeling the photosynthetic electron transport chain to downregulate photosynthetic activity and for protection against oxidative stress. Furthermore, we demonstrate that ppGpp is required for coupling chloroplastic and nuclear gene expression during nitrogen starvation. Altogether, our work indicates that ppGpp is a pivotal regulator of chloroplast activity for stress acclimation in plants.

Domaines: Biologie végétale; Biochimie, Biologie Moléculaire; Génétique

Shanna Romand, Hela Abdelkefi, Cecile Lecampion, Mohamed Belaroussi, Melanie Dussenne, et al.. A ppGpp-mediated brake on photosynthesis is required for acclimation to nitrogen limitation in Arabidopsis. 2021. ⟨hal-03353143⟩