Metabolic engineering example: Two genes from the bacterium Alcaligenes eutrophus combined with a cotton gene were used in plants to produce which type of product?

Introduction / Context:
Plant biochemical engineering often introduces entire pathways from microbes into crops to synthesize novel or valuable molecules. Alcaligenes eutrophus (now Cupriavidus necator) is famous for its polyhydroxyalkanoate (PHA) pathway that accumulates biodegradable plastics such as polyhydroxybutyrate (PHB). This question checks recognition of a landmark example in metabolic engineering of plants.

Given Data / Assumptions:

• Two bacterial genes from A. eutrophus were combined with a plant (cotton) gene.
• The intended product should be a recognizable engineered metabolite.
• Plants can be used as green factories for non-native polymers.

Concept / Approach:
A. eutrophus carries phbA, phbB, and phbC genes that convert acetyl-CoA to PHB. When the necessary genes (commonly phbA and phbB plus a suitable synthase) are expressed in plants, tissues can accumulate PHB granules. Cotton has been explored because fibers offer a convenient biomass for polymer accumulation.

Step-by-Step Solution:

Verification / Alternative check:
Multiple studies report transgenic Arabidopsis, cotton, and other plants producing PHB/PHAs using A. eutrophus genes, demonstrating polymer accumulation in different tissues.

Why Other Options Are Wrong:

• Vaccines/pharmaceuticals: not the classic A. eutrophus plant case.
• Herbicide resistance: requires detoxifying or target-site genes, not PHA enzymes.
• Insecticidal proteins: typically Bt genes, not PHA genes.

Common Pitfalls:
Confusing plastic-producing pathways (PHA/PHB) with unrelated transgenic traits like Bt or herbicide resistance.

Final Answer:
A biodegradable plastic (polyhydroxyalkanoate)