1BioEnergy Science Center, Oak Ridge National Laboratory (ORNL), 1 Bethel Valley Road, Oak Ridge, TN 37831 USA.
2Joint Institute for Biological Sciences, Biosciences Division, ORNL, 1 Bethel Valley Road, Oak Ridge, TN 37831 USA.
Commun Biol. 2019 Jan 17;2:22. doi: 10.1038/s42003-018-0265-6. eCollection 2019.
Knockdown (KD) expression of () in switchgrass improves sugar yield and ethanol production from the biomass. The reduced recalcitrance of -KD transgenic biomass is associated with reduced cell wall pectic homogalacturonan and rhamnogalacturonan II content and cross-linking, and the associated increases in accessibility of cellulose to enzymatic deconstruction. To further probe the molecular basis for the reduced recalcitrance of -KD biomass, potential recalcitrance-related factors including the physicochemical properties of lignin and hemicellulose are investigated. We show that the transgenic switchgrass have a lower abundance of ferulate and lignin-carbohydrate complex cross-linkages, reduced amounts of residual arabinan and xylan in lignin-enriched fractions after enzymatic hydrolysis, and greater coalescence and migration of lignin after hydrothermal pretreatment in comparison to the wild-type switchgrass control. The results reveal the roles of both decreased lignin-polymer and pectin cross-links in the reduction of recalcitrance in -KD switchgrass.
（）在柳枝稷中的敲低（KD）表达提高了生物质的糖产量和乙醇产量。-KD 转基因生物质的还原顽固性与减少的细胞壁果胶同质半乳糖醛酸聚糖和鼠李半乳糖醛酸聚糖 II 含量和交联有关，并且与纤维素对酶解的可及性增加有关。为了进一步探究 -KD 生物质还原顽固性的分子基础，研究了潜在的与顽固性相关的因素，包括木质素和半纤维素的物理化学性质。我们表明，转基因柳枝稷具有较低丰度的阿魏酸和木质素-碳水化合物复合物交联，在酶解后木质素富集部分中残留的阿拉伯聚糖和木聚糖减少，并且在水热处理预处理后木质素的聚合并迁移增加与野生型柳枝稷对照相比。结果揭示了木质素聚合物和果胶交联减少在 -KD 柳枝稷降低顽固性中的作用。
