Expression profile of phenylpropanoid pathway genes in Decalepis hamiltonii tuberous roots during flavour development

Abstract

To explore the transcriptional control of phenylpropanoid pathway (PPP) involved in vanillin flavour metabolites production in tuberous roots of , four PPP key genes expressed during the tuber development were identified and their mRNA expression profiles were evaluated using quantitative real-time PCR. Flavour metabolite quantification by HPLC analysis confirmed 10, 170 and 500 µg/g 2-hydroxy-4-methoxy benzaldehyde and 4, 20 and 40 µg/g vanillin in first- (3-month-old plant), second- (18-month-old plant) and third-stage tubers (60-month-old matured plant), respectively. The expression of all four genes phenylalanine ammonia lyase (DhPAL), cinnamate-4-hydroxylase (DhC4H), caffeic acid--methyltransferase (DhCOMT) and vanillin synthase (DhVAN) increased with flavour development from first stage to second stage. A decrease in expression from 1.9-folds to 0.1-folds and 19.2-folds to 5.2-folds for and was recorded for second stage to third stage, respectively. However, a gradual increase in expression of (up to 26.4-folds) and a constant expression pattern for (up to 7.1-folds) was evident from second stage to third stage of flavour development. The decrease in the expression levels of and in third stage shows that the second-stage tubers are more transcriptionally active towards flavour biosynthesis.

Physical characteristics, acceptability and biochemical properties of biscuits using Decalepis hamiltonii tuber extract as a natural flavouring agent

“…The major bioactive molecule of tuber constitutes 2‐hydroxy 4‐methoxybenzaldehyde, an isomer of vanillin (Nagarajan et al ., 2001), and successive attempts have been made by researchers to improve the flavour content of the D. hamiltonii tubers in vitro (Pradeep et al ., 2017; Koppada et al ., 2022) and ex vitro (Giridhar et al ., 2005; Pradeep et al ., 2019). Biochemical characterisation of key biosynthetic pathway steps involved in 2H4MB production (Kamireddy et al ., 2017) and proteomic and biotechnological approaches based on the identification of abundant proteins (Kamireddy et al ., 2021) and phenylpropanoid pathway genes expression (Kiran et al ., 2018) during flavour development were respectively investigated. Decalepis hamiltonii extract was listed in FDA regulations and is identified as generally recognised as safe (“GRAS”) substance.…”