Skip to main content
Figure 7 | BMC Genomics

Figure 7

From: De novo sequencing and characterization of Picrorhiza kurrooa transcriptome at two temperatures showed major transcriptome adjustments

Figure 7

Picrosides biosynthetic pathway in P. kurrooa (adapted from Kawoosa et al. and Dixon and Paiva [5, 59]). Picrosides are iridoid glycosides derived from cyclization of geranyl pyrophosphate (GPP) to iridoid moiety. Glucose and cinnamate/vanillate convert iridoid into picroside I and picroside II. These steps involve series of hydroxylation and glycosylation reactions catalyzed by cytochrome P450 and glycosyltransferases. GPP can be derived from mevalonate (MVA) or 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway. Enzymes of MVA pathway are as follows: AACT, acetyl-CoA acetyltransferase; HMGS, 3-hydroxy-3-methylglutaryl-CoA synthase; HMGR, 3-hydroxy-3-methylglutaryl-coenzyme A reductase; MVK, mevalonate kinase; PMK, phosphomevalonate kinase; PMD, diphosphomevalonate decarboxylase. Enzymes of MEP pathway are DXS, 1-deoxy-D-xylulose-5-phosphate synthase; DXR, 1-deoxy-D-xylulose-5-phosphate reductoisomerase; MCT, 2-C-methyl-D-erythritol 4-phosphate cytidylyltransferase; CMK, 4-diphosphocytidyl-2-C-methyl-D-erythritol kinase; MDS, 2-C-methyl-D-erythritol 2,4-cyclodiphosphate synthase; HDS, 4-hydroxy-3-methylbut-2-enyl diphosphate synthase; HDR, 4-hydroxy-3-methylbut-2-enyl diphosphate reductase. Isopentenyl pyrophosphate isomerase (IPPI) catalyzes the isomerisation of dimethylallyl pyrophosphate (DMAPP) to IPP whereas conversion of IPP to geranyl pyrophosphate (GPP) is catalyzed by geranyl pyrophosphate synthase (GPS). Enzyme of phenylpropanoid pathway involved in biosynthesis of cinnamate are PAL, phenylalanine ammonia-lyase; 4-CH, cinnamic acid 4-hydroxylase; 3-CH, p-coumarate 3-hydroxylase; COMT, caffeoyl-CoA 3-O methyltransferase. Solid arrows indicate known steps, whereas broken arrows represent unknown intermediates and enzymes. Numerals in parenthesis indicate fold change in gene expression at 15°C as compared to 25°C based on reads per exon kilobase per million (RPKM) values (detailed RPKM values are shown in Figure 8 and Additional file 13).

Back to article page