Key Laboratory of Forest Genetics and Biotechnology of Ministry of Education, Nanjing Forestry University, Nanjing, 210037, China; Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China; College of Forestry, Nanjing Forestry University, Nanjing, 210037, China.
Key Laboratory of Forest Genetics and Biotechnology of Ministry of Education, Nanjing Forestry University, Nanjing, 210037, China; Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China; College of Forestry, Nanjing Forestry University, Nanjing, 210037, China.
Plant Physiol Biochem. 2023 Aug;201:107879. doi: 10.1016/j.plaphy.2023.107879. Epub 2023 Jul 5.
As the most abundant renewable energy source, wood comprises the secondary cell wall (SCW). SCW biosynthesis involves lignin and cellulose deposition. Increasing studies have illustrated that R2R3-MYB transcription factors (TFs) play pivotal roles in affecting lignin accumulation and SCW formation. Nevertheless, the regulatory roles of R2R3-MYBs are still unresolved in Cryptomeria fortunei Hooibrenk cambium and wood formation. To dissect the potentials of CfMYBs, we successfully cloned and intensively studied the functions of CfMYB4 and CfMYB5 in SCW formation and abiotic stress response. They both contained the conserved MYB domain capable of forming a special structure that could bind to the core motifs of downstream genes. The phylogenetic tree implied that two CfMYBs clustered into different evolutionary branches. They were predominantly expressed in the stem and were localized to the nucleus. Furthermore, CfMYB4 functioned as an activator to enhance lignin and cellulose accumulation, and increase the SCW thickness by elevating the expression levels of SCW-related genes. By contrast, CfMYB5 negatively regulated lignin and cellulose biosynthesis, and decreased SCW formation by reducing the expression of SCW biosynthetic genes. Our data not only highlight the regulatory functions of CfMYBs in lignin deposition but also provide critical insights into the development of strategies for the genetic improvement of Cryptomeria fortunei wood biomass.
作为最丰富的可再生能源，木材由次生细胞壁（SCW）组成。SCW 的生物合成涉及木质素和纤维素的沉积。越来越多的研究表明，R2R3-MYB 转录因子（TFs）在影响木质素积累和 SCW 形成方面起着关键作用。然而，R2R3-MYBs 在柳杉形成层和木材形成中的调控作用仍未解决。为了剖析 CfMYBs 的潜力，我们成功克隆并深入研究了 CfMYB4 和 CfMYB5 在 SCW 形成和非生物胁迫响应中的功能。它们都包含保守的 MYB 结构域，能够形成一种特殊的结构，能够与下游基因的核心基序结合。系统发育树表明，两个 CfMYBs 聚类到不同的进化分支。它们主要在茎中表达，并定位于细胞核。此外，CfMYB4 作为激活剂发挥作用，通过提高 SCW 相关基因的表达水平，增强木质素和纤维素的积累，并增加 SCW 厚度。相比之下，CfMYB5 负调控木质素和纤维素的生物合成，并通过降低 SCW 生物合成基因的表达减少 SCW 的形成。我们的数据不仅突出了 CfMYBs 在木质素沉积中的调控功能，还为柳杉木材生物量的遗传改良策略的发展提供了重要的见解。
