Opines in crown gall tumors Which opine classes can be present in plant crown gall tissues induced by Agrobacterium?

Difficulty: Easy

Correct Answer: All of these

Explanation:


Introduction / Context:
Opines are unusual amino acid–derived compounds synthesized by T-DNA-transformed plant cells. Their profiles (octopine, nopaline, agropine, and related types) help classify Ti plasmids and confirm successful Agrobacterium-mediated transformation. Recognizing opine diversity is important for diagnostics and historical understanding of Ti plasmid biology.


Given Data / Assumptions:

  • Crown gall tissues carry integrated T-DNA expressing opine synthase genes.
  • Different Ti plasmid types encode different opine synthases.
  • Question asks which opines can be present overall, not in a single tumor simultaneously.


Concept / Approach:
Octopine-type Ti plasmids drive octopine synthesis; nopaline-type produce nopaline; agropine-type produce agropine and sometimes related opines. Hence, across crown gall cases, all these opines are encountered. Each opine type reflects the plasmid carried by the infecting Agrobacterium strain.


Step-by-Step Solution:

Identify opine classes: octopine, nopaline, agropine.Recall linkage: opine type ↔ Ti plasmid genotype.Note that the question asks inclusively about crown gall tissues in general.Select “All of these.”


Verification / Alternative check:
Paper chromatography and later HPLC analyses of tumor extracts historically distinguished octopine vs nopaline tumors, establishing the correlation between opine profile and Ti plasmid type.


Why Other Options Are Wrong:

  • Single opine choices ignore diversity across strains.
  • Normal plant amino acids: opines are novel conjugates not made by untransformed tissues.


Common Pitfalls:
Assuming a single tumor makes multiple unrelated opines; typically, the opine profile reflects the infecting plasmid type, not a mixture from all classes.


Final Answer:
All of these

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