Transcriptomic dissection underlying physiological and anatomical characteristics of poplar wood in response to changes in light intensity and nitrogen availability

To dissect the transcriptomic reprograming underlying the physiological and anatomical characteristics in the wood of Populus species in response to changes in light and nitrogen (N) availability, the saplings of P. alba x P. glandulosa were exposed to either control or high light intensity in combination with one of low, normal and high N levels. High light caused greater CO2 assimilation rate, higher concentrations of soluble sugars and starch, decreased enzymatic activities of NR and GS and increased activities of GOGAT and GDH, higher IAA and lower ABA, JA and SA contents, narrower fibers, and thinner thickness of fiber wall in the wood of poplars under normal N condition. Low N supply led to greater levels of sucrose and starch, lower contents of most amino acids, IAA, ABA and JA, and narrower vessels and fibers, and high N caused the opposite effects in poplar wood exposed to control light. Transcriptomic reprograming occurred underlying the physiological and anatomical changes of P. alba x P. glandulose in acclimation to high light in combination with one of low, normal and high N levels. High light-and low/high N-induced differential expression of the key genes including neutral invertases, ASN1, JAZ1, and TIP1;3, involved in the metabolism of carbohydrate, amino acids and phytohormones, and water transport, corresponded well to changes in physiological and anatomical characteristics in poplar wood in response to high light and altered N availability. These results suggest that physiological and anatomical char-acteristics are altered in the wood and the underlying transcriptomic reprograming is critical for the wood in acclimation to high light in combination with changing N availability.

Automated summary

To understand the physiological and anatomical changes in the wood of Populus species under different light and nitrogen availability, researchers conducted experiments on Populus alba x P. glandulosa saplings exposed to control or high light intensity with low, normal, or high levels of nitrogen. The results showed that high light led to increased CO2 assimilation rate, higher concentrations of sugars and starch, changes in enzyme activities, phytohormone contents, fiber characteristics, and thickness of fiber wall in the wood. Changes in gene expression related to carbohydrate and amino acid metabolism, phytohormones, and water transport corresponded to these physiological and anatomical changes. It suggests that transcriptomic reprogramming plays a critical role in the acclimation of wood to changing light and nitrogen availability.