Origin of opine synthesis In Agrobacterium-induced crown gall tissues, the capacity to synthesize opines is best described as:

Introduction / Context:
Opines are signature metabolites produced by transformed plant cells in crown gall tumors. Their presence underpins early diagnostics of transformation and historically guided the classification of Ti plasmids. The question probes whether you understand that opine synthesis is plant-executed yet bacterially dictated.

Given Data / Assumptions:

• T-DNA integrates into the plant genome and is expressed by plant transcriptional machinery.
• The specific opine produced depends on the opine synthase genes carried on the Ti plasmid.
• Untransformed plant cells do not synthesize opines.

Concept / Approach:
After transformation, plant cells gain new genes (within T-DNA) that encode opine synthases. Thus, the biochemical capacity resides in plant cells, but its genetic origin is the bacterium’s plasmid. Consequently, both statements are simultaneously true: the plant gains the trait, and its nature is determined by the bacterium’s Ti plasmid type (octopine, nopaline, agropine).

Step-by-Step Solution:

Verification / Alternative check:
Tumor tissues maintained in vitro without bacteria continue producing the same opines, proving that plant cells themselves carry and express the opine synthase genes acquired from Agrobacterium.

Why Other Options Are Wrong:

• Only (a) or only (b): each is incomplete alone.
• Normal plant cells or bacterial-only pathway: contradicts the transformation mechanism and tumor biochemistry.

Common Pitfalls:
Assuming opine production ceases without bacteria present; once integrated, the plant genome encodes the trait autonomously.

Final Answer:
Both (a) and (b)