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.

Spatholobus suberectus Dunn  /  SsLAR2  /  catechin  /  bioinformatics  /  gene function