CEPR1 regulates Arabidopsis thaliana root architecture by modulating auxin production via NIT1

Like all organisms, plants must make decisions about growth that ultimately lead to their conservation or expenditure of energy. Carbon and nitrogen are both critical macronutrients required for growth and survival, and plants must be able to sense the internal abundance of both to ensure that there is enough to either commit to growth or avoid wasting resources on growth when environmental conditions are suboptimal. In Arabidopsis thaliana, the receptor-like kinase CEPR1 is involved in a regulatory pathway that comprises a systemic signaling network that can influence root system architecture depending on the availability of both carbon and nitrogen. Here, we present evidence that CEPR1 can integrate nitrogen and carbon status to influence lateral root growth through genetic interactions with the auxin biosynthetic enzyme, NITRILASE 1 (NIT1), and that genetic interactions between CEPR1 and NIT1 can affect auxin levels in the primary root and in inflorescence stems. Additionally, we show that mutations in NIT1 can suppress an infertility phenotype associated with CEPR1 mutations. Overall, our results suggest a model that CEPR1 regulates development under different amounts of carbon and nitrogen by modulating auxin production via NIT1.