Study of dynamics of genes involved in biosynthesis and accumulation of scopoletin at different growth stages of Convolvulus prostratus Forssk

Abstract

The scopoletin one of the major bioactive components of Convolvulus prostratus Forssk known to have a role in acetylcholinesterase inhibitor, memory enhancer, antimicrobial, antioxidative etc. properties are investigated in the present study. The concentration of scopoletin in C. prostratus is investigated in leaf, stem and root at different growth stages of plant development viz., 30, 45, 60 and 90 days after sowing (DAS). A highly sensitive LC-MS method was developed to quantify the scopoletin even at low concentration with LOD and LOQ of 8 and 24 ng/ml, respectively. The highest quantity of scopoletin was recorded in stem (732 μg/g dry weight) and leaf (650 μg/g dry weight) collected 90 DAS whereas lowest was recorded at 45 DAS in leaf (90.00 μg/g dry weight) and Stem (110 μg/g dry weight). Based on the highest and lowest concentration of scopoletin in stem and root tissues at 45 and 90 DAS were selected for transcriptome study. Differential gene expression analysis revealed the differential expression of genes involved in scopoletin biosynthesis. Seven genes viz., phenylalanine ammonia-lyase (PAL), 4-coumarate CoA ligase (4CL), trans-cinnamate 4-monooxygenase (TCM), shikimate O- hydroxycinnamoyl transferase (C3’H), 5-O-4-coumaroyl-D-quinate 3'-monooxygenase (HCT), caffeoyl-CoA-O-methyltransferase (CCoAOMT) and feruloyl-CoA 6'-hydroxylase (F6’H) were identified in the phenyl propanoid pathway. Expression of the novel enzyme F6′H showed down regulation in both tissues at 45 DAS. Real-time PCR showed a correlation with the expression of this F6′H genes with the accumulation of scopoletin at 90 DAS. This indicated that the growth stage of plant and expression of F6′H control the scopoletin accumulation in Convolvulus. The results of present investigation may useful in pharmaceutical, drug and cosmetic industries that the harvesting of plant part especially stem of C.prostratus at 90 DAS to get maximum quantity of scopoletin. Also, the novel gene F6′H need to be further characterized to understand its expression dynamics so that scopoletin content can be increase at the highest.