Dumitrache Alexandru, Natzke Jace, Rodriguez Miguel, Yee Kelsey L, Thompson Olivia A, Poovaiah Charleson R, Shen Hui, Mazarei Mitra, Baxter Holly L, Fu Chunxiang, Wang Zeng-Yu, Biswal Ajaya K, Li Guifen, Srivastava Avinash C, Tang Yuhong, Stewart Charles Neal, Dixon Richard A, Nelson Richard S, Mohnen Debra, Mielenz Jonathan, Brown Steven D, Davison Brian H
BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
Plant Biotechnol J. 2017 Jun;15(6):688-697. doi: 10.1111/pbi.12666. Epub 2017 Feb 20.
Transgenic Panicum virgatum L. silencing (KD) or overexpressing (OE) specific genes or a small RNA (GAUT4-KD, miRNA156-OE, MYB4-OE, COMT-KD and FPGS-KD) was grown in the field and aerial tissue analysed for biofuel production traits. Clones representing independent transgenic lines were established and senesced tissue was sampled after year 1 and 2 growth cycles. Biomass was analysed for wall sugars, recalcitrance to enzymatic digestibility and biofuel production using separate hydrolysis and fermentation. No correlation was found between plant carbohydrate content and biofuel production pointing to overriding structural and compositional elements that influence recalcitrance. Biomass yields were greater for all lines in the second year as plants establish in the field and standard amounts of biomass analysed from each line had more glucan, xylan and less ethanol (g/g basis) in the second- versus the first-year samples, pointing to a broad increase in tissue recalcitrance after regrowth from the perennial root. However, biomass from second-year growth of transgenics targeted for wall modification, GAUT4-KD, MYB4-OE, COMT-KD and FPGS-KD, had increased carbohydrate and ethanol yields (up to 12% and 21%, respectively) compared with control samples. The parental plant lines were found to have a significant impact on recalcitrance which can be exploited in future strategies. This summarizes progress towards generating next-generation bio-feedstocks with improved properties for microbial and enzymatic deconstruction, while providing a comprehensive quantitative analysis for the bioconversion of multiple plant lines in five transgenic strategies.
将沉默（KD）或过表达（OE）特定基因或小RNA（GAUT4-KD、miRNA156-OE、MYB4-OE、COMT-KD和FPGS-KD）的转基因柳枝稷种植在田间，并对地上组织进行生物燃料生产特性分析。建立了代表独立转基因株系的克隆，并在第1年和第2年生长周期后采集衰老组织样本。使用单独水解和发酵法分析生物质的细胞壁糖、对酶消化的抗性以及生物燃料生产情况。未发现植物碳水化合物含量与生物燃料生产之间存在相关性，这表明存在影响抗性的主要结构和组成元素。由于植物在田间定植，所有株系在第二年的生物量产量更高，与第一年的样本相比，从每个株系分析的标准生物量量在第二年含有更多的葡聚糖、木聚糖和更少的乙醇（以克/克为基础），这表明多年生根系再生后组织抗性普遍增加。然而，与对照样本相比，针对细胞壁修饰的转基因株系（GAUT4-KD、MYB4-OE、COMT-KD和FPGS-KD）第二年生长的生物质具有更高的碳水化合物和乙醇产量（分别高达12%和21%）。发现亲本株系对抗性有显著影响，这可在未来策略中加以利用。这总结了在培育具有改进的微生物和酶解特性的下一代生物原料方面取得的进展，同时为五种转基因策略中多个植物株系的生物转化提供了全面的定量分析。
