# DBT JRF 2020 — Question 71

Exam: DBT JRF 2020 · Section: B · Topic: Biotechnology · Difficulty: Medium

## Question

During Agrobacterium infections, plant cell begins to synthesize Arginine derivatives called

## Options

- **A.** Acetobenzylpurine
- **B.** Opines
- **C.** Acetosyringone
- **D.** Hygromycin

## Answer

Option B

## Explanation

During Agrobacterium tumefaciens infection of plant cells: The bacterium attaches to wounded plant cells and senses phenolic wound signals (acetosyringone). The Ti (tumour-inducing) plasmid contains T-DNA (transfer DNA) and vir (virulence) genes. Vir proteins nick and transfer T-DNA as a single-stranded copy into the plant cell, where it integrates into the nuclear genome. T-DNA encodes: Ipt (isopentenyltransferase for cytokinin biosynthesis), iaaM+iaaH (for auxin biosynthesis — causing crown gall tumour), and OPINE SYNTHASE genes. Opines are condensation products of amino acids with $\alpha$ -ketoacids or sugars — e.g. nopaline (Arg + $\alpha$ -ketoglutarate), octopine (Arg + pyruvate), agropine. Agrobacterium catabolises opines using plasmid-encoded enzymes for carbon and nitrogen nutrition. Acetosyringone is the phenolic signal that induces vir genes, not the opine. Hygromycin is a selection antibiotic used in plant transformation.

Source: https://mypyqbuddy.com/questions/during-agrobacterium-infections-plant-cell-begins-to-synthesize-6a05a8a02adafec47029325f