Responses to Systemic Nitrogen Signaling in Arabidopsis Roots Involve trans-Zeatin in Shoots. Issue 6 (15th May 2018)

• Record Type: Journal Article
• Authors: Poitout, Arthur; Crabos, Amandine; Petřík, Ivan; Novák, Ondrej; Krouk, Gabriel; Lacombe, Benoît; Ruffel, Sandrine
• Is Part Of: The Plant Cell. Volume 30:Issue 6(2018)
• Page Start: 1243
• Page End: 1257
• Publication Date: 2018-05-15
• DOI: 10.1105/tpc.18.00011
• Languages: English
• ISSNs: 1040-4651

Abstract

Abstract : The level of the cytokinin trans -zeatin in shoots controls the molecular, physiological, and growth responses of nitrate-supplied roots in a root system facing heterogeneous nitrate availability. Abstract: Plants face temporal and spatial variation in nitrogen (N) availability. This includes heterogeneity in soil nitrate (NO3 − ) content. To overcome these constraints, plants modify their gene expression and physiological processes to optimize N acquisition. This plasticity relies on a complex long-distance root-shoot-root signaling network that remains poorly understood. We previously showed that cytokinin (CK) biosynthesis is required to trigger systemic N signaling. Here, we performed split-root experiments and used a combination of CK-related mutant analyses, hormone profiling, transcriptomic analysis, NO3 − uptake assays, and root growth measurements to gain insight into systemic N signaling in Arabidopsis thaliana . By comparing wild-type plants and mutants affected in CK biosynthesis and ABCG14-dependent root-to-shoot translocation of CK, we revealed an important role for active trans -zeatin ( t Z) in systemic N signaling. Both rapid sentinel gene regulation and long-term functional acclimation to heterogeneous NO3 − supply, including NO3 − transport and root growth regulation, are likely mediated by the integration of tZ content in shoots. Furthermore, shoot transcriptome profiling revealed that glutamate/glutamine metabolism is likely a target of t Z root-to-shoot translocation, prompting an interesting hypothesis regarding shoot-to-root communication. Finally, this study highlights t Z-independent pathways regulating gene expression in shoots as well as NO3 − uptake activity in response to total N deprivation.