title: Phosphorus and nitrogen physiology of two contrasting poplar genotypes when exposed to phosphorus and/or nitrogen starvation.
abstract: Phosphorus (P) and nitrogen (N) are the two essential macronutrients for tree growth and development. To elucidate the P and N physiology of woody plants during acclimation to P and/or N starvation, we exposed saplings of the slow-growing Populus simonii Carr (Ps) and the fast-growing Populus × euramericana Dode (Pe) to complete nutrients or starvation of P, N or both elements (NP). P. × euramericana had lower P and N concentrations and greater P and N amounts due to higher biomass production, thereby resulting in greater phosphorus use efficiency/N use efficiency (PUE/NUE) compared with Ps. Compared with the roots of Ps, the roots of Pe exhibited higher enzymatic activities in terms of acid phosphatases (APs) and malate dehydrogenase (MDH), which are involved in P mobilization, and nitrate reductase (NR), glutamate synthase (GOGAT) and glutamate dehydrogenase (GDH), which participate in N assimilation. The responsiveness of the transcriptional regulation of key genes encoding transporters for phosphate, ammonium and nitrate was stronger in Pe than in Ps. These results suggest that Pe possesses a higher capacity for P/N uptake and assimilation, which promote faster growth compared with Ps. In both poplars, P or NP starvation caused significant decreases in the P concentrations and increases in PUE. Phosphorus deprivation induced the activity levels of APs, phosphoenolpyruvate carboxylase and MDH in both genotypes. Nitrogen or NP deficiency resulted in lower N concentrations, amino acid levels, NR and GOGAT activities, and higher NUE in both poplars. Thus, in Ps and Pe, the mRNA levels of PHT1;5, PHT1;9, PHT2;1, AMT2;1 and NR increased in the roots, while PHT1;9, PHO1;H1, PHO2, AMT1;1 and NRT2;1 increased in the leaves during acclimation to P, N or NP deprivation. These results suggest that both poplars suppress P/N uptake, mobilization and assimilation during acclimation to P, N or NP starvation.
authors.affiliation: College of Life Sciences and State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, Shaanxi 712100, PR China.
authors.forename: Honghao
authors.initials: H
authors.lastname: Gan
authors.affiliation: Key Laboratory of Environment and Ecology in Western China of Ministry of Education, College of Forestry, Northwest A&F University, Yangling, Shaanxi 712100, PR China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Jiao
authors.affiliation: College of Life Sciences and State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, Shaanxi 712100, PR China.
authors.forename: Jingbo
authors.initials: J
authors.lastname: Jia
authors.affiliation: Key Laboratory of Environment and Ecology in Western China of Ministry of Education, College of Forestry, Northwest A&F University, Yangling, Shaanxi 712100, PR China.
authors.forename: Xinli
authors.initials: X
authors.lastname: Wang
authors.affiliation: College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, PR China.
authors.forename: Hong
authors.initials: H
authors.lastname: Li
authors.affiliation: College of Life Sciences and State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, Shaanxi 712100, PR China.
authors.forename: Wenguang
authors.initials: W
authors.lastname: Shi
authors.affiliation: Key Laboratory of Environment and Ecology in Western China of Ministry of Education, College of Forestry, Northwest A&F University, Yangling, Shaanxi 712100, PR China.
authors.forename: Changhui
authors.initials: C
authors.lastname: Peng
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: College of Life Sciences and State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, Shaanxi 712100, PR China Key Laboratory of Environment and Ecology in Western China of Ministry of Education, College of Forestry, Northwest A&F University, Yangling, Shaanxi 712100, PR China luozbbill@163.com.
authors.forename: Zhi-Bin
authors.initials: ZB
authors.lastname: Luo
mesh_terms: D000064:Acclimatization; D005838:Genotype; D009584:Nitrogen / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism*; D032107:Populus / Q000235:genetics / Q000378:metabolism*
chemical_list: D010758:Phosphorus; D009584:Nitrogen
keywords: nutrient deficiency; nutrient use efficiency; phosphate transporter; phosphorus metabolism; transcriptional regulation; tree