Nookaraju Akula, Pandey Shashank K, Ahlawat Yogesh K, Joshi Chandrashekhar P
Department of Biological Sciences, Michigan Technological University, Houghton, MI 49931, USA.
Kaveri Seed Company Limited, Secunderabad 500003, Telangana, India.
Plants (Basel). 2022 Feb 11;11(4):493. doi: 10.3390/plants11040493.
Lignocellulosic biomass from the secondary cell walls of plants has a veritable potential to provide some of the most appropriate raw materials for producing second-generation biofuels. Therefore, we must first understand how plants synthesize these complex secondary cell walls that consist of cellulose, hemicellulose, and lignin in order to deconstruct them later on into simple sugars to produce bioethanol via fermentation. homeobox () genes encode homeodomain-containing transcription factors (TFs) that modulate various important developmental processes in plants. While genes are mainly expressed in the shoot apical meristems of both monocot and eudicot plants and are involved in meristem maintenance and/or formation, genes exhibit diverse expression patterns and their precise functions have mostly remained unknown, until recently. The expression patterns of genes in , namely and , suggest that TFs encoded by at least some of these genes, such as and , may play a significant role in secondary cell wall formation. Specifically, the expression of the gene is regulated by upstream TFs, such as SND1 and MYB46, while KNAT7 interacts with other cell wall proteins, such as KNAT3, MYB75, OFPs, and BLHs, to regulate secondary cell wall formation. Moreover, KNAT7 directly regulates the expression of some xylan synthesis genes. In this review, we summarize the current mechanistic understanding of the roles of Class II KNOX TFs in secondary cell wall formation. Recent success with the genetic manipulation of Class II KNOX TFs suggests that this may be one of the biotechnological strategies to improve plant feedstocks for bioethanol production.
来自植物次生细胞壁的木质纤维素生物质确实有潜力提供一些最合适的原料来生产第二代生物燃料。因此，我们必须首先了解植物如何合成这些由纤维素、半纤维素和木质素组成的复杂次生细胞壁，以便之后将它们分解成单糖，通过发酵生产生物乙醇。同源异型框（）基因编码含同源异型结构域的转录因子（TFs），这些转录因子调节植物中的各种重要发育过程。虽然基因主要在单子叶植物和双子叶植物的茎尖分生组织中表达，并参与分生组织的维持和/或形成，但直到最近，基因仍表现出多样的表达模式，其确切功能大多未知。基因在中的表达模式，即和，表明这些基因中至少有一些编码的转录因子，如和，可能在次生细胞壁形成中发挥重要作用。具体而言，基因的表达受上游转录因子如SND1和MYB46的调控，而KNAT7与其他细胞壁蛋白如KNAT3、MYB75、OFP和BLH相互作用，以调节次生细胞壁的形成。此外，KNAT7直接调控一些木聚糖合成基因的表达。在本综述中，我们总结了目前对II类KNOX转录因子在次生细胞壁形成中作用的机制理解。最近对II类KNOX转录因子进行基因操作取得的成功表明，这可能是改善用于生物乙醇生产的植物原料的生物技术策略之一。
