目的 克隆鸡血藤（密花豆Spatholobus suberectus的干燥藤茎）无色花色素还原酶基因SsLAR2，开展生物信息学及基因功能研究，以期解析其在儿茶素生物合成中的作用。方法 以鸡血藤cDNA作为模板，通过RT-PCR技术克隆SsLAR2，并对其开展系统的生物信息学分析。构建SsLAR2过表达载体，遗传转化本氏烟草，测定转基因植株中总黄酮含量、儿茶素含量以及儿茶素合成途径中关键酶基因的表达水平。结果 SsLAR2基因全长1 092 bp，编码363个氨基酸，相对分子质量为40 513.75，等电点为5.75。SsLAR2蛋白为亲水性蛋白，存在跨膜区域，与木豆、毒羊豆及相思子等多种植物中的LAR蛋白同源性较高。SsLAR2启动子序列中包含光响应元件，以及茉莉酸甲酯、赤霉素、水杨酸等多种植物激素的响应元件。基因功能分析表明，过表达SsLAR2能显著提高转基因植株中总黄酮和儿茶素的含量以及儿茶素合成途径中关键酶基因的表达水平。结论 鸡血藤SsLAR2基因能够促进植物的儿茶素合成，为深入解析鸡血藤儿茶素生物合成的调控机制，开展相关的分子育种工作提供重要的基因资源和理论依据。

Objective To clone the leucoanthocyanidin reductase gene SsLAR2 from Spatholobi Caulis (dried rattan stem of Spatholobus suberectus), and conduct bioinformatics and function verification, in order to elucidate the role of SsLAR2 gene in the biosynthesis of catechin. Methods SsLAR2 was amplified from the cDNA of Spatholobi Caulisvia RT-PCR and conducted systematic bioinformatics analysis. The SsLAR2 overexpression vector was constructed and genetically transformed into Nicotiana benthamiana. The total flavonoid content, catechin content, and the expression levels of key enzyme genes in the catechin synthesis pathway were determined in the transgenic plants. Results The full length of SsLAR2 gene was 1 092 bp in length, encoding 363 amino acids. The molecular weight of SsLAR2 protein was 40 513.75, and the isoelectric point was 5.75. The SsLAR2 protein was a hydrophilic protein with a transmembrane region, showing high homology with LAR proteins from various plants such as Cajanus cajan, Gastrolobium bilobum and Abrus precatorius. The promoter sequence of SsLAR2 contained photoresponsive elements, as well as responsive elements for multiple plant hormones such as methyl jasmonate, gibberellin, and salicylic acid. Gene functional analysis revealed that overexpression of SsLAR2 significantly increased the total flavonoid and catechin contents, as well as the expression levels of key enzyme genes in the catechin biosynthetic pathway in the transgenic plants. Conclusion Heterologous expression of SsLAR2 can promote catechin biosynthesis in plants. This gene provides important genetic materials and a theoretical basis for in-depth dissection of the regulatory mechanisms underlying catechin biosynthesis and targeted molecular breeding of Spatholobi Caulis.

R282.12

国家重点研发计划（2024YFC3506703）；广西自然科学基金项目（2025GXNSFAA069354，2020GXNSFBA159006）；广西中医药适宜技术开发与推广项目（GZSY2025005）