Phenylalanine as a nitrogen source induces root growth and nitrogen-use efficiency in Populus × canescens. (19th September 2017)

• Record Type: Journal Article
• Authors: Jiao, Yu; Chen, Yinghao; Ma, Chaofeng; Qin, Jingjing; Nguyen, Thi Hong Nhung; Liu, Di; Gan, Honghao; Ding, Shen; Luo, Zhi-Bin
• Is Part Of: Tree physiology. Volume 38:Number 1(2018)
• Page Start: 66
• Page End: 82
• Publication Date: 2017-09-19
• Subjects: amino acids -- aromatic and neutral amino acids transporter -- nitrogen-use efficiency -- organic nitrogen -- phenylalanine -- phenylalanine ammonia lyase -- root characteristics -- transcriptional regulation; Trees -- Physiology -- Periodicals; 582.16
• DOI: 10.1093/treephys/tpx109
• Languages: English
• ISSNs: 0829-318X

Abstract

Abstract: To investigate the physiological responses of poplars to amino acids as sole nitrogen (N) sources, Populus × canescens (Ait.) Smith plants were supplied with one of three nitrogen fertilizers (NH4 NO3, phenylalanine (Phe) or the mixture of NH4 NO3 and Phe) in sand culture. A larger root system, and decreased leaf size and CO2 assimilation rate was observed in Phe- versus NH4 NO3 -treated poplars. Consistently, a greater root biomass and a decreased shoot growth were detected in Phe-supplied poplars. Decreased enzymatic activities of nitrate reductase (NR), glutamate synthase (GOGAT) and glutamate dehydrogenase (GDH) and elevated activities of nitrite reductase (NiR), phenylalanine ammonia lyase (PAL), glutamine synthetase (GS) and asparagine synthase (AS) were found in Phe-treated roots. Accordingly, reduced concentrations of NH4 +, NO3 − and total N, and enhanced N-use efficiencies (NUEs) were detected in Phe-supplied poplars. Moreover, the transcript levels of putative Phe transporters ANT1 and ANT3 were upregulated, and the mRNA levels of NR, glutamine synthetase 2 (GS2), NADH-dependent glutamate synthase (NADH - GOGAT), GDH and asparagine synthetase 2 (ASN2) were downexpressed in Phe-treated roots and/or leaves. The 15 N-labeled Phe was mainly allocated in the roots and only a small amount of 15 N-Phe was translocated to poplar aerial parts. These results indicate that poplar roots can acquire Phe as an N source to support plant growth and that Phe-induced NUEs in the poplars are probably associated with NH4 + re-utilization after Phe deamination and the carbon bonus simultaneously obtained during Phe uptake.