# DBT JRF 2022 — Question 84

Exam: DBT JRF 2022 · Section: B · Topic: Plant Biotechnology › Metabolic Engineering - MEP Pathway · Difficulty: Medium

## Question

In a metabolic engineering experiment the flux from primary carbon metabolism was diverted towards methylerythritol phosphate (MEP) pathway. Which one of the following class of secondary carbon compounds do you think will accumulate more?

## Options

- **A.** Alkaloids
- **B.** Glucosinolates
- **C.** Phenolics
- **D.** Terpenes

## Answer

Option D

## Explanation

MEP pathway and terpenoid accumulation in plants: Terpenoids (isoprenoids) are the largest class of natural products in plants, synthesised from IPP (isopentenyl diphosphate) and DMAPP (dimethylallyl diphosphate). Two pathways produce IPP/DMAPP: 1. MVA (Mevalonate) pathway: in cytosol → produces IPP for sesquiterpenes (C15), sterols (C30), triterpenoids. 2. MEP (2-C-Methyl-D-erythritol-4-phosphate) pathway: in plastids → produces IPP for monoterpenes (C10), diterpenes (C20), carotenoids (C40), and gibberellins. To increase terpenoid accumulation: • Divert primary carbon flux (e.g., from glycolysis/pyruvate) toward the MEP pathway. • Overexpress rate-limiting MEP pathway enzymes (DXS: 1-deoxy-D-xylulose-5-phosphate synthase is often rate-limiting). • This increases IPP/DMAPP pool → more terpene building blocks → higher terpenoid accumulation. Answer: Diverting primary carbon flux toward the MEP pathway increases plastidic terpenoid/terpene accumulation.

Source: https://mypyqbuddy.com/questions/in-a-metabolic-engineering-experiment-the-flux-from-6a104cd5920734408bc0c763