Oroxylum indicum, (L.) Kurz

Deshmukh, Aaditi B., Datir, Sagar S., Bhonde, Yogesh, Kelkar, Natasha, Samdani, Pawan & Tamhane, Vaijayanti A., 2018, De novo root transcriptome of a medicinally important rare tree Oroxylum indicum for characterization of the flavonoid biosynthesis pathway, Phytochemistry 156, pp. 201-213 : 206

2.7. Expression pattern of selected phenylpropanoid and flavonoid biosynthesis pathway genes in the young and mature roots of O. indicum

Relative expression levels of seven genes namely, cinnamyl alcohol dehydrogenase (OinCAD), 4-coumarate–CoA ligase (Oin4CL), transcinnamate 4-monooxygenase (OinC4H), chalcone synthase (OinCHS), flavone synthase (OinFNS), chalcone isomerase (OinCHI) and flavanone 3-dioxygenase (OinF3H) were determined by a quantitative real time polymerase chain reaction (qRT-PCR) ( Fig. 4 ) in young and old roots of O. indicum . The expression level of OinCAD was not significantly different in the two tissues. A two fold higher expression of Oin4CL was detected in old roots as compared to young roots. The expression of OinC4H was lower in both the young and old root of O. indicum . OinCHS showed around a four fold higher expression in the old root as compared to the young root ( Fig. 4 ). CHS is the first rate-limiting enzyme in flavonoid biosynthesis pathway and higher levels of the enzyme is directly correlated with the higher level of flavonoids (Zuk et al., 2016). On the contrary, expression of OinCHI, OinFNS and OinF3H were at least ten fold higher in young roots as compared to old roots of O. indicum ( Fig. 4 ). The higher expression of CHI in young roots may be linked to its role in auxin movement leading to plant growth and development ( Peer and Murphy, 2007). Moreover, there are possibly different isoforms of the flavonoid biosynthesis genes which display spatial and temporal regulation, as reflected by their differential expression in young and old roots of O. indicum .

Figures

Fig. 4. Expression pattern of selected genes from phenylpropanoid and flavonoid biosynthetic pathway using qRT-PCR. Seven genes involved in phenylpropanoid and flavonoid biosynthesis namely, cinnamyl alcohol dehydrogenase (OinCAD), 4-coumarate–CoA ligase (Oin4CL), Trans-cinnamate 4-monooxygenase (OinC4H), chalcone synthase (OinCHS), flavone synthase (OinFNS), chalcone isomerase (OinCHI) and flavanone 3-dioxygenase (OinF3H) were selected for qRT-PCR analysis. The results represent the means ± standard error of experiments performed in triplicate. The data (n = 5) was analyzed using Student's t-test (*p ≤ 0.05, **p ≤ 0.01 and ***p ≤ 0.001).