%A YIN Neng-Wen**,LI Jia-Na**,LIU Xue,LIAN Jian-Ping,FU Chun,LI Wei,JIANG Jia-Yi,XUE Yu-Fei,WANG Jun,CHAI You-Rong* %T Lignification Response and the Difference between Stem and Root of Brassica napus under Heat and Drought Compound Stress %0 Journal Article %D 2017 %J Acta Agronomica Sinica %R 10.3724/SP.J.1006.2017.01639 %P 1689-1695 %V 43 %N 11 %U {https://zwxb.chinacrops.org/CN/abstract/article_6366.shtml} %8 2017-11-12 %X

Using histochemical, biochemical, and gas chromatography-mass spectrometry (GC-MS) technologies, the responsive trends of xylem structure and lignin components in the stem and the root of rapeseed (Brassica napus) cultivar Zhongshuang 10 under heat and drought stresses were investigated as compared with normal-growth plants. Histochemical staining of the frozen sections showed that, compared with the cage-grown plants (normal plants), the plants grown in greenhouse (stressed plants) had a thicker xylem part in both stem and root, with deeper staining color. Correspondingly, the total lignin content in the stem of stressed plants tested by acetyl bromide method increased by 31.64% compared with that of the normal plants. Besides, heat and drought compound stress reduced vessel inner diameter in the stem, while increased both vessel number and vessel inner diameter in the root. Stem total lignin monomer yield prepared by thioacidolysis of stressed plants was 40.08% lower than that of the normal plants, indicating higher condensed bonds in stressed plants. Meanwhile, the S/G ratio (1.82) was significantly higher than that of the normal plants (1.29), indicating increased proportion of S units and decreased proportion of G units. Furthermore, this study also revealed the difference of lignification traits between the stem and the root. The stem had lower condensed bonds and major proportion of S units (S/G=1.29), while the root had more condensed bonds and major proportion of G units (S/G=0.49). Moreover, the H unit percentage in the root (7.43%) was almost 10 folds as that in the stem (0.83%). Since H and G units have lower methylation levels and are easier to form condensed bonds, the high proportions of H and G units might be the main reason for the high proportion of condensed bonds in root lignin structure.