Department of Plant Biology, Institute of Biology, University of Campinas, Campinas, Brazil.
Academic Department of Biology, Professional and Academic School of Biology, Universidad Nacional de San Agustín de Arequipa, Arequipa, Perú.
GM Crops Food. 2024 Dec 31;15(1):67-84. doi: 10.1080/21645698.2024.2325181. Epub 2024 Mar 20.
The agricultural sugarcane residues, bagasse and straws, can be used for second-generation ethanol (2GE) production by the cellulose conversion into glucose (saccharification). However, the lignin content negatively impacts the saccharification process. This polymer is mainly composed of guaiacyl (G), hydroxyphenyl (H), and syringyl (S) units, the latter formed in the ferulate 5-hydroxylase (F5H) branch of the lignin biosynthesis pathway. We have generated transgenic lines overexpressing under the control of the (cinnamate 4-hydroxylase) rice promoter, which led to a significant increase of up to 160% in the S/G ratio and 63% in the saccharification efficiency in leaves. Nevertheless, the content of lignin was unchanged in this organ. In culms, neither the S/G ratio nor sucrose accumulation was altered, suggesting that overexpression would not affect first-generation ethanol production. Interestingly, the bagasse showed a significantly higher fiber content. Our results indicate that the tissue-specific manipulation of the biosynthetic branch leading to S unit formation is industrially advantageous and has established a foundation for further studies aiming at refining lignin modifications. Thus, the overexpression in sugarcane emerges as an efficient strategy to improve 2GE production from straw.
农业甘蔗渣、蔗渣和秸秆可通过纤维素转化为葡萄糖（糖化）用于第二代乙醇（2GE）生产。然而，木质素含量会对糖化过程产生负面影响。该聚合物主要由愈创木基（G）、对羟苯基（H）和丁香基（S）单元组成，后者在木质素生物合成途径的阿魏酸 5-羟化酶（F5H）分支中形成。我们已经生成了过量表达的转基因系，该基因在 的控制下（肉桂醇 4-羟化酶）水稻启动子，导致叶片中 S/G 比增加了高达 160%，糖化效率增加了 63%。然而，该器官中的木质素含量没有变化。在茎秆中，S/G 比和蔗糖积累都没有改变，这表明 过量表达不会影响第一代乙醇的生产。有趣的是，蔗渣的纤维含量明显更高。我们的结果表明，对导致 S 单元形成的生物合成分支的组织特异性操作在工业上是有利的，并为旨在改进木质素修饰的进一步研究奠定了基础。因此，在甘蔗中过量表达 成为提高秸秆 2GE 生产的有效策略。
