Analyses of Microstructure and Dynamic Deposition of Cell Wall Components in Xylem Provide Insights into Differences between Two Black Poplar Cultivars

Abstract

The chemical composition of the cell wall varies between species and even within the same species, and impacts the properties of the cell wall. In this study, the dynamic chemical compositions of the xylem cell walls of two black poplar cultivars, Populus × euramericana ‘Zhonglin46’ and Populus × euramericana ‘Neva,’ were investigated in situ using stimulated Raman scattering microscopy (SRS). Meanwhile, the pectin structural features were examined using immunofluorescence methods. The results showed that Neva displayed faster thickening of the fiber cell walls than Zhonglin46 did, and it had a greater cell wall thickness in mature xylem. A faster deposition speed of lignin and cellulose during xylem maturation was revealed in Neva. Significantly higher lignin contents were found in the mature xylem of Neva compared with those of Zhonglin46, while no obvious differences in cellulose deposition in mature xylem were observed between the two cultivars. The patterns of pectin deposition during xylem maturation were similar in the two cultivars, but more pectin was found in the mature xylem of Neva than in that of Zhonglin46. The chemical deposition patterns account for the anatomical feature differences between the cultivars. These results provide valuable insights into the chemical deposition and anatomical differences between cultivars, and they might be helpful in understanding the wood growth processes and facilitating the utilization of different poplar cultivars.