[Transcriptome analysis and catechin synthesis genes in different organs of Spatholobus suberectus]

To study the differences in transcript levels among different organs of Spatholobus suberectus and to explore the genes encoding enzymes related to the catechin biosynthesis pathway, this study utilized the genome and full-length transcriptome data of S. suberectus as references. Transcriptome sequencing and bioinformatics analysis were performed on five different organs of S. suberectus-roots, stems, leaves, flowers, and fruits-using the Illumina NovaSeq 6000 platform. A total of 115.28 Gb of clean data were obtained, with GC content values ranging from 45.19% to 47.54%, Q20 bases at 94.17% and above, and an overall comparison rate with the reference genome around 90%. In comparisons between the stem and root, stem and leaf, stem and flower, and stem and fruit, 10 666, 9 674, 9 320, and 5 896 differentially expressed genes(DEGs) were identified, respectively. The lowest number of DEGs was found in the stem and root comparison group. KEGG enrichment analysis revealed that the DEGs were mainly concentrated in the pathways of phytohormone signaling, phenylalanine biosynthesis, etc. A total of 39 genes were annotated in the catechin biosynthesis pathway, with at least one highly expressed gene found in all organs. Among these, PAL1, PAL2, C4H1, C4H3, 4CL1, 4CL2, and DFR2 showed high expression in the stems, suggesting that they may play important roles in the biosynthesis of flavonoids in S. suberectus. This study aims to provide important information for the in-depth exploration of the regulation of catechin biosynthesis in S. suberectus through transcriptome analysis of its different organs and to provide a reference for the further realization of S. suberectus varietal improvement and molecular breeding.