【目的】木聚糖是双子叶植物中次生壁半纤维素的主要成分,在维持植物次生壁的完整性和植物生长方面有重要作用。在木本植物中,木聚糖对木材性质和生物质能源的利用有重要影响。本研究探索我国南方速生树种团花树NcIRX9基因及其在木聚糖合成中的功能。【方法】结合生物信息学方法,分析团花树NcIRX9亲缘关系和蛋白质结构;构建 YFP( 黄色荧光蛋白) 融合蛋白,观察其亚细胞定位;通过qRT-PCR分析团花树NcIRX9基因的表达特性及组织特异性;通过切片显微观察、化学免疫、单糖分析及H¹-NMR分析团花树NcIRX9基因在拟南芥突变体irx9体内的功能。【结果】团花树NcIRX9在进化上保守,其N端存在一个信号肽,定位于高尔基体内,与拟南芥AtIRX9密切相关。NcIRX9基因在根、茎、叶、木质部、韧皮部均有表达,且在木质部中的表达量较高。互补分析表明NcIRX9能部分互补拟南芥突变体irx9表型,是AtIRX9的直系同源基因。此外,本研究还表明在拟南芥突变体irx9过度表达NcIRX9木糖含量升高,侧链信号增强,与此同时还原末端侧链信号增强。【结论】团花树NcIRX9基因行使与拟南芥AtIRX9相似的生物学功能,与木聚糖的合成密切相关。

【Objective】Xylan is the major component of secondary wall hemicellulose in dicot plants and plays an indispensable role in maintaining plant secondary wall integrity and plant growth. Xylan also greatly impacts wood properties and biomass energy. The study described here explores theIRX9 gene of Neolamarckia cadamba, a fast-growing tree species in southern China. Furthermore, the role of NcIRX9 in xylan biosynthesis is also explored. 【Method】 Bioinformatics was used to analyze NcIRX9 protein structure. A yellow fluorescent protein (YFP) fusion protein was constructed NcIRX9, and its subcellular localization was observed. Both NcIRX9 expression in different tissues were analyzed by qRT-PCR. In addition, by tissue sectioning and microscopic observation, chemical immunization, monosaccharide analysis, and H¹-NMR analysis, we verified the function of NcIRX9. NcIRX9 function was further validated in a mutant Arabidopsis model. 【Result】 NcIRX9 is evolutionarily conserved and contains a signal peptide at its N-terminus, closely related toArabidopsis AtIRX9, which is located in the Golgi. The NcIRX9 gene is expressed in the roots, stems, leaves, xylem and phloem, with its highest level of expression in the xylem. We determined that NcIRX9 can partially rescue the Arabidopsis mutant irx9 phenotype, as it is orthologous to AtIRX9. Moreover, this study also demonstrated that overexpression of NcIRX9 in Arabidopsis irx9 mutants increases xylose content, side chain signal enhancement, and reduces the end side chain signal enhancement. 【Conclusion】 The biological function of the NcIRX9 gene in Neolamarckia cadamba is similar to that of Arabidopsis AtIRX9 and is highly involved in xylan biosynthesis.