title: Global poplar root and leaf transcriptomes reveal links between growth and stress responses under nitrogen starvation and excess.
abstract: Nitrogen (N) starvation and excess have distinct effects on N uptake and metabolism in poplars, but the global transcriptomic changes underlying morphological and physiological acclimation to altered N availability are unknown. We found that N starvation stimulated the fine root length and surface area by 54 and 49%, respectively, decreased the net photosynthetic rate by 15% and reduced the concentrations of NH4+, NO3(-) and total free amino acids in the roots and leaves of Populus simonii Carr. in comparison with normal N supply, whereas N excess had the opposite effect in most cases. Global transcriptome analysis of roots and leaves elucidated the specific molecular responses to N starvation and excess. Under N starvation and excess, gene ontology (GO) terms related to ion transport and response to auxin stimulus were enriched in roots, whereas the GO term for response to abscisic acid stimulus was overrepresented in leaves. Common GO terms for all N treatments in roots and leaves were related to development, N metabolism, response to stress and hormone stimulus. Approximately 30-40% of the differentially expressed genes formed a transcriptomic regulatory network under each condition. These results suggest that global transcriptomic reprogramming plays a key role in the morphological and physiological acclimation of poplar roots and leaves to N starvation and excess.
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Luo
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Applied Entomology, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Li
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China.
authors.forename: Wenguang
authors.initials: W
authors.lastname: Shi
authors.affiliation: Büsgen-Institute, Department of Forest Botany and Tree Physiology, Georg-August University, Büsgenweg 2, 37077 Göttingen, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Polle
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China.
authors.forename: Mengzhu
authors.initials: M
authors.lastname: Lu
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China.
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Sun
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China luozbbill@163.com.
authors.forename: Zhi-Bin
authors.initials: ZB
authors.lastname: Luo
mesh_terms: D004305:Dose-Response Relationship, Drug; D009566:Nitrates / Q000378:metabolism*; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D032107:Populus / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D017422:Sequence Analysis, DNA; D013312:Stress, Physiological; D059467:Transcriptome
chemical_list: D009566:Nitrates; D010940:Plant Proteins; C006568:ammonium nitrate
keywords: Populus; RNA sequencing; nutrient physiology; phytohormone; woody plants