Marta Gallart1, Camila Cambui5, Peter Clinton2, Jiangming Xue2, Dean Meason3, Matthew Turnbull1, Karen Adair1,4, Jonathan Love1,5, Torgny Näsholm5
1 Centre for Integrative Ecology, School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand.
2 ScionResearch, P.O. Box 2923, Christchurch, New Zealand
3 ScionResearch, Private Bag 3020, Rotorua, New Zealand
4 Department of Entomology, Cornell University, Ithaca, NY 14853 United States
5 Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
Is nitrogen just nitrogen from a plant´s perspective or does the form of nitrogen, inorganic or organic, matter? In this paper we combine data from several experiments in which the form of nitrogen (N) supplied to plant, but not the amount, was varied. We present data from a breadth of systems spanning the model plant Arabidopsis where intrinsic responses in carbon (C) allocation patterns could be observed in the absence of microbial interactions on sterile agar to pot-grown conifer trees where a DNA metabarcoding approach was used to describe the root associated microbiome. Taken together, these studies point to a fundamental difference between organic and inorganic N as nutritional sources for plants and microbes. Our results provide evidence that organic N, in contrast to inorganic N, promotes growth of roots, root hairs and mycorrhizal fungi. Biochemical shifts in C contents of shoots and roots suggest a C-bonus from organic compared to inorganic N, possibly explained by a smaller fraction of C partitioned to N assimilation.