Bruise-resistant tomato development — antisense RNA was targeted against which enzyme to reduce softening?

Introduction / Context:
Post-harvest softening and bruising in tomatoes are largely due to the breakdown of pectin in the cell wall. The Flavr Savr™ approach used antisense technology to downregulate a key pectin-degrading enzyme and thereby improve firmness.

Given Data / Assumptions:

• Antisense strategy reduces the target mRNA and thus enzyme activity.
• Polygalacturonase (PG) hydrolyzes pectate chains in the middle lamella.
• Goal was reduced softening and improved bruise resistance.

Concept / Approach:

Targeting the polygalacturonase gene by antisense RNA diminishes pectin depolymerization and slows softening. Other listed enzymes do not directly address the main softening pathway in tomato fruit (e.g., SPS affects sucrose metabolism; ACC deaminase modulates ethylene levels, which is indirect).

Step-by-Step Solution:

Verification / Alternative check:

Published reports of Flavr Savr™ document antisense PG reducing softening and extending shelf life.

Why Other Options Are Wrong:

Glycerol-1-phosphate acyltransferase is for lipid synthesis; ACC deaminase reduces ethylene but is not the core approach used; SPS is unrelated to pectin breakdown; pectin methylesterase is involved in demethylation but the classic antisense target for bruise resistance was PG.

Common Pitfalls:

Confusing general ethylene manipulation with specific cell-wall enzyme suppression.

Final Answer:

Polygalacturonase