Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing, China.
National Engineering Research Center of Tree Breeding and Ecological Restoration, College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, China.
Nat Plants. 2022 Jul;8(7):828-839. doi: 10.1038/s41477-022-01181-3. Epub 2022 Jul 18.
At present, a cooperative process hypothesis is used to explain the supply of enzyme (class III peroxidases and/or laccases) and substrates during lignin polymerization. However, it remains elusive how xylem cells meet the needs of early lignin rapid polymerization during secondary cell wall formation. Here we provide evidence that a mitochondrial ascorbate peroxidase (PtomtAPX) is responsible for autonomous lignification during the earliest stage of secondary cell wall formation in Populus tomentosa. PtomtAPX was relocated to cell walls undergoing programmed cell death and catalysed lignin polymerization in vitro. Aberrant phenotypes were caused by altered PtomtAPX expression levels in P. tomentosa. These results reveal that PtomtAPX is crucial for catalysing lignin polymerization during the early stages of secondary cell wall formation and xylem development, and describe how xylem cells provide autonomous enzymes needed for lignin polymerization during rapid formation of the secondary cell wall by coupling with the programmed cell death process.
目前，人们用合作过程假说来解释酶（III 类过氧化物酶和/或漆酶）和底物在木质素聚合过程中的供应。然而，木质部细胞如何在次生细胞壁形成过程中满足早期木质素快速聚合的需求仍然难以捉摸。在这里，我们提供的证据表明，在毛白杨次生细胞壁形成的最早阶段，线粒体抗坏血酸过氧化物酶（PtomtAPX）负责自主木质化。PtomtAPX 被重新定位到正在发生程序性细胞死亡的细胞壁上，并在体外催化木质素聚合。毛白杨中 PtomtAPX 表达水平的改变导致了异常表型。这些结果表明，PtomtAPX 对于催化次生细胞壁形成早期阶段和木质部发育过程中的木质素聚合至关重要，并描述了木质部细胞如何通过与程序性细胞死亡过程偶联，为次生细胞壁快速形成过程中所需的自主木质素聚合提供酶。
