柚木心材和边材的LC-MS代谢组学比较

Comparative metabolomics analysis on heartwood and sapwood components of teak(Tectona grandis)

为阐明柚木心边材次生代谢产物,明确心边材的差异代谢物及其代谢途径,采用超高效液相色谱联用质谱分析方法,结合主成分分析(PCA)、正交-偏最小二乘法判别分析(OPLS-DA)等统计分析方法,对柚木的心边材进行了代谢组学分析。基于人体代谢组数据库(HMDB)分析,从6株柚木心边材样本中共鉴定出705个代谢物,包括脂类和类脂类180个、含氧有机物类120个、苯丙素和聚酮类101个、有机杂环化合物82个、有机酸及其衍生物58个和苯环衍生物49个等。心材中相对含量最高的代谢物为环烯醚萜苷kanokoside A,边材中相对含量最高的代谢物为4-羟基-5-(3′,4′-二羟基苯基)-戊酸-O-甲基-O-葡萄糖醛酸苷。PCA和OPLS-DA分析显示,从心边材中共鉴定出差异代谢物328个,包括脂类和类脂类69个、苯丙素和聚酮类57个、含氧有机物50个、有机杂环化合物41个、有机酸及其衍生物24个、苯环衍生物23个、核苷/核苷酸和类似物8个、含氮有机物2个、生物碱及其衍生物2个、木脂素/新木脂素及相关化合物1个和其他类型化合物51个。与边材相比,心材中共有235个代谢物上调,93个代谢物下调。差异代谢物中有28个代谢物被注释到了代谢、遗传信息处理和环境信息处理等3大类基因组百科全书数据库(KEGG)代谢通路中,进一步分析发现大多数差异代谢物被富集到各类氨基酸代谢和黄酮类生物合成等代谢通路中。其中,心边材中相对含量前30的显著差异代谢物在心材中均得到上调,且均含有不饱和结构和共轭结构,推测它们可能与柚木心边材颜色明显差异有关。

In order to clarity the different secondary metabolites and their metabolic pathways in heartwood(HW)and sapwood(SW)of teak(Tectona grandis),a comparative metabolomics analysis on HW and SW of teak planted in 1995 in the Yingjiang state-owned forest farm,Dehong County,Yunnan Province was carried out,using the ultra-performance liquid chromatography-triple-time of flight mass spectrometer(UPLC-Triple-TOF-MS)combined with statistical analysis methods,such as the principal component analysis(PCA)and orthogonal-partial least squares discriminant analysis(OPLS-DA).Based on the analysis of the Human Metabolome Database(HMDB),a total of 705 metabolites including 180 lipids and lipid-like molecules(25.53%),120 organic oxygen compounds(17.02%),101 phenylpropanoids and polyketides(14.33%),82 organoheterocyclic compounds(11.63%),58 organic acids and derivatives(8.23%),and 49 benzenoids(6.95%),were identified in 6 teak trees.The lipids and lipid-like metabolites are the most abundant components in teak,and the kanokoside A and 4-hydroxy-5-(3′,4′-dihydroxyphenyl)-valeric acid-O-methyl-O-glucuronide were the metabolites with the highest contents in HW and SW,respectively.The PCA and OPLS-DA analyses showed that 328 different metabolites were identified between HW and SW,including 69 lipids and lipid-like molecules(21.04%),57 phenylpropanoids and polyketides(17.38%),50 organooxygen compounds(15.24%),41 organoheterocyclic compounds(12.50%),24 organic acids and derivatives(7.32%),23 benzenoids(7.01%),eight nucleosides,nucleotides,and analogues(2.44%),two organic nitrogen compounds(0.61%),two alkaloids and derivatives(0.61%),one lignan/neolignan or related compound(0.30%),and 51 other compounds(15.55%).Compared with SW,235 metabolites were up-regulated and 93 ones were down-regulated in HW.Among the different metabolites in HW and SW,28 compounds are annotated into the three categories of Kyoto Encyclopedia of Genes and Genomes(KEGG)metabolic pathways including the metabolism,genetic information processing and environmental information processing,and a large number of different metabolites were found further to be enriched in amino acid metabolism and flavonoid biosynthetic pathways.Among which,the top 30 significant different metabolites with unsaturated and aromatic conjugate structure in HW and SW were all up regulated in HW,which might be related to the obvious color difference in the HW and SW of teak.The results obtained in this study can provide a scientific basis for the further clarify of the coloring mechanism of teak heartwood and the wood improvement of teak.