Proteomic reprogramming underlying anatomical and physiological characteristics of poplar wood in acclimation to changing light and nitrogen availabilities

To explore the proteomic regulation that underlies the physiological, anatomical, and chemical characteristics of wood in acclimation to changing light and nitrogen (N), saplings of Populus × canescens were treated with control or high irradiance in combination with low, control or high N for 4 months. High irradiance led to elevated levels of starch, sucrose, glucose, and fructose, decreased concentrations of ammonium, nitrate, most amino acids and total N, wider xylem, more xylem cell layers, narrower vessel lumina, longer fiber cells, greater fiber wall thickness, and more cellulose and hemicellulose but less lignin deposition in poplar wood. Limiting N resulted in increased levels of starch and sucrose, reduced levels of glucose, fructose, ammonium, nitrate, amino acids and total N, narrower xylem, fewer xylem cell layers, reduced vessel lumen diameter, thicker fiber walls, and less cellulose and more hemicellulose and lignin accumulation, whereas high N had the opposite effects on poplar wood. Correspondingly, numerous differentially abundant proteins, which are related mainly to the metabolism of carbohydrates and amino acids, cell division and expansion, and deposition of secondary cell walls, such as sucrose synthase 6 (SUS6), cell division cycle protein 48 (CDC48) and laccases (LACs), were identified in poplar cambiums in response to changes in light intensity and N availability. These results suggest that proteomic relays play essential roles in regulating the physiological characteristics and anatomical and chemical properties of poplar wood in acclimation to changing light and N availabilities.