Abstract Field-grown genetically engineered and wild-type poplars were pyrolyzed in a micro-pyrolysis (Py-GC/MS) setup under fast pyrolysis conditions. Poplars (Populus tremula x P. alba) down-regulated for cinnamoyl-CoA reductase (CCR), which catalyzes the first step of the monolignol-specific branch of the phenylpropanoid biosynthetic pathway, were grown in field trials in France and harvested after a full rotation of 2 years. The effect of small compositional differences, specifically small shifts in lignin composition and their impact on the bio-oil composition, could not be identified using principal component analysis (PCA), necessitating the use of more advanced analysis techniques. The combination of parallel factor analysis 2 (PARAFAC2) and partial least squares-discriminant analysis (PLS-DA) for detailed characterization and classification of the pyrolysis data enabled the classification of the poplars with a success rate above 99% using the PARAFAC2 scores. This methodology proved to be extremely valuable to identify subtle information in complex datasets, such as the one used in this study. The obtained PLS-DA models were validated by cross-validation, jackknifing and permutation tests in order to ensure that the model was not overfitting the data. PLS-DA showed that down-regulation of CCR disfavored the relative amount of both guaiacyl and syringyl lignin-derived compounds. This study shows that lignin engineering can be a promising strategy to alter the lignin composition of the biomass for the production of high value-added phenolic compounds.

中文翻译：

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Py-GC/MS 结合 PARAFAC2 和 PLS-DA 在基因工程杨树快速热解研究中的应用

摘要 在快速热解条件下，在微热解 (Py-GC/MS) 装置中对田间种植的基因工程杨树和野生型杨树进行热解。杨树 (Populus tremula x P. alba) 的肉桂酰辅酶 A 还原酶 (CCR) 下调，该酶催化苯丙烷生物合成途径的单木质醇特异性分支的第一步，在法国的田间试验中生长，并在完全2年轮换。使用主成分分析 (PCA) 无法确定小成分差异的影响，特别是木质素成分的小变化及其对生物油成分的影响，因此需要使用更先进的分析技术。并行因子分析 2 (PARAFAC2) 和偏最小二乘判别分析 (PLS-DA) 相结合，用于详细表征和分类热解数据，使用 PARAFAC2 分数使杨树分类的成功率超过 99%。事实证明，这种方法对于识别复杂数据集中的细微信息非常有价值，例如本研究中使用的数据。获得的 PLS-DA 模型通过交叉验证、jackknifing 和置换测试进行验证，以确保模型不会过度拟合数据。PLS-DA 显示 CCR 的下调不利于愈创木酰和丁香酰木质素衍生化合物的相对量。