Revealing the relationship between nitrogen use efficiency‐related QTLs and carbon and nitrogen metabolism regulation in poplar

Abstract

AbstractPoplar provides a large amount of bioenergy and wood, but the lack of soil nitrogen in poplar plantations has seriously restricted its wood production. Using Populus deltoides ‘Danhong’, P. simonii ‘Tongliao1’, and their F1 populations as materials, nitrogen fertilizer and no nitrogen fertilizer were applied in the field. Under different nitrogen conditions, the wood yield of ‘Danhong’ was much higher than that of ‘Tongliao 1’, which indicated that ‘Danhong’ had excellent genetic resources related to nitrogen use efficiency (NUE). Based on a high‐density genetic map, we performed quantitative trait loci (QTL) analyses for ground diameter, plant height, stem biomass, and nitrogen response index. A total of 276 QTLs and 774 candidate genes were identified. We analysed the metabolites related to carbon and nitrogen metabolism and the transcriptome of the developing xylem in 10 clones under high‐ and low‐nitrogen conditions. Through weighted gene coexpression network analysis, it was found that the MEyellow module was closely related to biomass, carbon, and nitrogen metabolism, and a gene coexpression network was established. Finally, candidate genes NRT3.1, NPF5.1, NPF5.10, and NPF8.1 related to nitrogen transport; transcription factors NLP8.1, NLP8.2, and NLP2 regulating nitrogen transport; genes Potri.010G070900, GDH2, and SHM2 related to amino acid metabolism; and genes Necap2, Dscr3, trappc2l, Potri.013G072600, and LAX2 related to carbon metabolism were identified. This work provides abundant genetic resources for the genetic improvement of poplar NUE and provides new insights into the linkage mechanism between NUE and biomass yield.