Nitrate foraging by Arabidopsis roots is mediated by the transcription factor TCP20 through the systemic signaling pathway

• Published in: Proceedings of the National Academy of Sciences - PNAS 2014-10, Vol.111 (42), p.15267-15272
• Main Authors: Guan, Peizhu, Wang, Rongchen, Nacry, Philippe, Breton, Ghislain, Kay, Steve A., Pruneda-Paz, Jose L., Davani, Ariea, Crawford, Nigel M.
• Format: Article
• Language: English
• Subjects: Arabidopsis; Arabidopsis - metabolism; Arabidopsis Proteins - metabolism; Biological Sciences; Cycloidea; Deoxyribonucleic acid; DNA; Ecosystem; Enhancer Elements, Genetic; Escherichia coli - metabolism; Flowers & plants; Foraging; Gene Expression Regulation, Plant - drug effects; Genes; Homozygote; Life Sciences; Mutation; Nitrates; Nitrates - metabolism; Nitrogen; Nitrogen - metabolism; Phenotype; Plant Physiological Phenomena; Plant roots; Plant Roots - metabolism; Plant Shoots - metabolism; Plants; Promoter Regions, Genetic; Quaternary ammonium compounds; Root growth; Signal Transduction - drug effects; Soil Microbiology; Transcription factors; Transcription Factors - metabolism; Vegetal Biology; Yeast
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1411375111

To compete for nutrients in diverse soil microenvironments, plants proliferate lateral roots preferentially in nutrient-rich zones. For nitrate, root foraging involves local and systemic signaling; however, little is known about the genes that function in the systemic signaling pathway. By using nitrate enhancer DNA to screen a library of Arabidopsis transcription factors in the yeast one-hybrid system, the transcription factor gene TEOSINTE BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR1-20 (TCP20) was identified. TCP20, which belongs to an ancient plant-specific gene family that regulates shoot, flower, and embryo development was implicated in nitrate signaling by its ability to bind DNA in more than 100 nitrate-regulated genes. Analysis of insertion mutants of TCP20 showed that they had normal primary and lateral root growth on homogenous nitrate media but were impaired in preferential lateral root growth (root foraging) on heterogeneous media in split-root plates. Inhibition of preferential lateral root growth was still evident in the mutants even when ammonium was uniformly present in the media, indicating that the TCP20 response was to nitrate. Comparison of tqp20 mutants with those of nlp7 mutants, which are defective in local control of root growth but not in the root-foraging response, indicated that TCP20 function is independent of and distinct from NLP7 function. Further analysis showed that tqp20 mutants lack systemic control of root growth regardless of the local nitrate concentrations. These results indicate that TCP20 plays a key role in the systemic signaling pathway that directs nitrate foraging by Arabidopsis roots.