Protein farnesylation is involved in nitrogen starvation adaptation in Arabidopsis

Nitrogen is an important element that controls plant growth and yield. Recently we showed that protein farnesylation is involved in nitrate-driven root architecture organization in Arabidopsis. In this study, we aimed to deeper investigate the role of this post-translational maturation in plant responses to nitrogen, by studying the metabolic and phenotypic adaptations of the era1.8 mutant (enhanced response to abscisic acid 1; i.e. lacking protein farnesylation activity) to various NH4NO3 supplies. WT and era1.8 plants were grown on low-nitrogen substrate supplemented with 0, 2 or 10 mM NH4NO3, and were analyzed for biomass production and carbon- and nitrogen-related metabolites. Our results showed that compared to WT, era1.8 developed exacerbated responses to N starvation, i.e. a higher root/shoot ratio, a higher anthocyanins content and a higher carbon/nitrogen ratio. Moreover, transcriptomic analyzes revealed an over-expression of several genes related to nitrogen starvation adaptation in era1.8 and pointed out two genes encoding uncharacterized farnesylated proteins. At 2 and 10 mM NH4NO3, although the era1.8 mutant displayed a higher biomass, its metabolism and gene expression are comparable to that of WT. Overall, our results show that era1.8 develops exacerbated responses to nitrogen starvation with specific metabolic balances, highlighting that protein farnesylation participates to plant adaptation to nitrogen nutritional stress.