杉木应压木木质部细胞形态特征及主要代谢成分表征

Morphological characteristics of cells and main metabolic components in xylem of Cunninghamia lanceolata compression wood

为探讨主要代谢成分与应压木形成的关系,以拉弯诱导形成的杉木应压木为材料,在明确其重要显微特征、木质素含量的基础上,运用气相色谱质谱联用系统(GC-MS)对主要代谢成分进行了鉴定和相对表达丰度分析。结果表明:杉木应压木管胞多以椭圆形呈现,且管胞壁明显增厚。应压木管胞平均长度和宽度分别为1 347.34和20.18μm,均显著小于对应木;平均壁腔比为0.43,显著大于对应木。应压木木质素的相对含量较对应木增加21.9%。在3个拉弯时期皆可鉴定出18种代谢成分,其中有机酸5种、单糖4种、二糖3种、醇类和氨基酸各2种、无机酸和内酯类各1种。时期Ⅰ应压木中果糖和葡萄糖含量与对应木差异不大,但这2种化合物含量均随拉弯时间延长呈现下降趋势,且时期Ⅱ、Ⅲ在应压木中的含量显著小于对应木,符合应压木纤维素含量下降的事实。应压木中与木质素合成相关的莽草酸含量呈上升趋势,其在时期Ⅲ应压木中的含量显著高于对应木,这解释了应压木中木质素含量明显多于对应木的现象。

To explore the relationship between major metabolic components and the formation of compression wood（ CW）,we took the Cunninghamia lanceolata CW induced by bending as the study material,and then clarified the anatomic characteristics and lignin contents of C. lanceolata CW. Further we used GCMS to indentify the major metabolic components from the developed xylem and analyzed the relative abundance. The results showed that the most of CW tracheids were oval and developed with thick cell walls. Average length and width of CW tracheids were 1 347. 34 μm and 20. 18 μm respectively,which were significantly less than those of opposite wood（ OW）. The average ratio of cell wall to lumen was0. 43,obviously higher than that of OW. The relative content of CW increased by 21. 9% compared with the OW. Eighteen known metabolites and isomers could be identified at the three treatment periods,which were classified into six categories. The saccharides represented the largest group（ 7 =monosaccharide 4 ＋ disaccharide 3）,followed by organic acid（ 5）,alcohol（ 2） and amino acid（ 2）,inorganic acid（ 1） and lactone（ 1）. By the comparison of metabolite contents between CW and OW in the period I,we found that there was a slight difference in the contents of fructose and glucose; however,both fructose and glucose decreased gradually as bending treatment progressed,and their contents in CW were both less than those in OW at the period Ⅱ and Ⅲ. This was in line with the fact of cellulose content decreasing in CW. In addition,shikimic acid associated with the lignin biosynthesis was detected in this experiment. The ratio of this compound showed a rising trend as bending time prolonged,and its content in CW was obviously higher than that in OW at the period Ⅲ,which might partly explain the reason of higher lignin content in CW.