Ferulate-5-hydroxylase (F5H) is a key rate-limiting enzyme for the conversion of guaiacyl monolignol (G-monolignol) to syringyl monolignol (S-monolignol) in the specific synthetic lignin pathway, through the catalysis of the 5-hydroxylation of S-monolignol precursors ferulic acid, conifer aldehyde, and coniferyl alcohol. In this study, we cloned the F5H gene of Populus tomenta (PtoF5H), whose product has a highly conserved domain of P450-dependent monooxygenase family. Subcellular localization result demonstrated that PtoF5H protein is an endoplasmic reticulum (ER) resident protein. Furthermore, the PtoF5H was transformed into tobacco in the form of sense- and antisense-, showed that the proportion of S-monolignol increased when PtoF5H gene was overexpressed, suggesting PtoF5H could be used as a target gene for modifying lignin composition. These findings provide further insight into the function of PtoF5H.

阿魏酸5-羟化酶（F5H）是关键的限速酶，通过特定的合成木质素途径，将愈创木脂单木酚（G-单酚）转化为丁香基单木酚（S-单酚），通过催化5-羟化S-monolignol前体是阿魏酸，松柏树醛和松柏醇。在这项研究中，我们克隆了毛白杨的F5H基因（PtoF5H），其产物具有高度保守的P450依赖单加氧酶家族结构域。亚细胞定位结果表明PtoF5H蛋白是内质网（ER）驻留蛋白。此外，PtoF5H以有义和反义形式转化为烟草，表明当PtoF5H基因过表达，提示PtoF5H可用作修饰木质素组成的靶基因。这些发现提供了进一步了解PtoF5H的功能。