Journal: bioRxiv

Article Title: Interactomics-driven discovery of alkaloid biosynthetic pathways in kratom

doi: 10.64898/2026.05.01.722234

Figure Lengend Snippet: a) Transcriptional profiles of 60 positive interactors and the upstream MIA-pathway genes across 49 published kratom transcriptomes were analyzed, and genes exhibiting co-expression patterns are shown. Each column represents a biological replicate, and each row corresponds to a distinct gene. Expression levels are shown as Z-scores calculated from log 2 -normalized TPM values, ranging from −1.4 (blue, lower expression) to +5.1 (red, higher expression). Among the 60 putative interacting MsMDRs, three functional and interacting MsMDRs, such as MsMDR141, MsMDR290, and MsDCS1, were highly expressed in roots from samples with high mitragynine levels (Root 1) and young leaves. Other genes highly expressed include MsSLS, MsSTR, Ms7DLGT, MsTDC, MsCPR, Ms8HGO, MsLAMT1, and MsIO in the strictosidine biosynthetic pathway. Sample descriptors include: Root 1 (high-mitragynine), Root 2 (low-mitragynine), Leaf 2 (leaf bract), and Leaf 3 (leaf after wounding). b) Genomic mapping of the three co-expressed MsMDRs identified a 320-kb biosynthetic gene cluster in Tig00011620 scaffold. Green: previously reported MsMDRs, including MsDCS1, 3, 4, a truncated version of MsDCS3, and MsMDR4; Red: newly discovered functional MsMDRs, including MsMDR141 (three isogenes), MsMDR290, and MsMDR320. Black: putative interacting MsMDRs that did not exhibit activity in biochemical screening. Abbreviations: MDR, medium-chain dehydrogenase/reductase; SLS, secologanin synthase; STR, strictosidine synthase; 7-DLGT, 7-deoxyloganetic acid-O-glucosyl transferase; TDC, tryptophan decarboxylase; DCS, dihydrocorynantheine synthase; CPR, NADPH-cytochrome P450 reductase; 8-HGO, 8-hydroxygeraniol oxidoreductase; LAMT, loganic acid O-methyltransferase; IO, 7-deoxyloganetic acid synthase/iridoid oxidase.

Article Snippet: Dextrose, yeast extract (YE), peptone, Luria-Bertani (LB) broth, LB agar, Terrific broth (TB), agar, acetonitrile, formic acid, imidazole, β-nicotinamide adenine dinucleotide phosphate reduced tetrasodium salt (NADPH) and protease inhibitor (100x) were purchased from Thermo Fisher Scientific.

Techniques: Expressing, Gene Expression, Functional Assay, Activity Assay