High nitrogen fertilization and stem leaning have overlapping effects on wood formation in poplar but invoke largely distinct molecular pathways

Abstract

Previous studies indicated that high nitrogen fertilization may impact secondary xylem development and alter fibre anatomy and composition. The resulting wood shares some resemblance with tension wood, which has much thicker cell walls than normal wood due to the deposition of an additional layer known as the G-layer. This report compares the short-term effects of high nitrogen fertilization and tree leaning to induce tension wood, either alone or in combination, upon wood formation in young trees of Populus trichocarpa (Torr. & Gray) × P. deltoides Bartr. ex Marsh. Fibre anatomy, chemical composition and transcript profiles were examined in newly formed secondary xylem. Each of the treatments resulted in thicker cell walls relative to the controls. High nitrogen and tree leaning had overlapping effects on chemical composition based on Fourier transform infrared analysis, specifically indicating that secondary cell wall composition was shifted in favour of cellulose and hemicelluloses relative to lignin content. In contrast, the high-nitrogen trees had shorter fibres, whilst the leaning trees had longer fibres that the controls. Microarray transcript profiling carried out after 28 days of treatment identified 180 transcripts that accumulated differentially in one or more treatments. Only 10% of differentially expressed transcripts were affected in all treatments relative to the controls. Several of the affected transcripts were related to carbohydrate metabolism, secondary cell wall formation, nitrogen metabolism and osmotic stress. RT-qPCR analyses at 1, 7 and 28 days showed that several transcripts followed very different accumulation profiles in terms of rate and level of accumulation, depending on the treatment. Our findings suggest that high nitrogen fertilization and tension wood induction elicit largely distinct and molecular pathways with partial overlap. When combined, the two types of environmental cue yielded additive effects.

N-fertilization has different effects on the growth, carbon and nitrogen physiology, and wood properties of slow- and fast-growing Populus species

“…7B, 7C). A stimulation of G-layer formation under higher N supply has been observed in other poplar species and is associated with N-induced changes in secondary wall chemical composition and gene expression (Pitre et al ., 2010). The dimensions of vessel elements and fibre cells were characterized in both poplar species (see Supplementary Fig.…”

Gypsophile Chemistry Unveiled: Fourier Transform Infrared (FTIR) Spectroscopy Provides New Insight into Plant Adaptations to Gypsum Soils

“…It has been used to detect changes in plant chemistry in relation to fertilization [22], [23], [24] or heavy metal addition [25], [26], [27]. FTIR spectra analysed through artificial neural networks (NN) show a high potential to discriminate biological samples.…”

Ash content, carbon and C/N ratio in paricá in function of NPK fertilization

“…timber, a species normally used for such energy ends. According to Pitre et al (2010), the soil´s natural characteristics and fertilization are factors that affect timber quality. Changes in growth conditions caused by fertilizers are associated with alterations in timber quality with regard to their physical, chemical and anatomical characteristics.…”