Assertion: GMO tomato i.e., "Flavr Savr" has increased shelf life and better nutrient quality.
Reason: This is achieved by reducing the amount of cell wall degrading enzyme "polygalacturonase" responsible for fruit softening.

Both Assertion (A) and Reason(R) are correct and R is the correct explanation of A.

Genetically modified tomato i.e., flavr savr show delayed ripening. By the use of antisense RNA technology the enzyme polygalacturonase, that causes damage to pectin is deactivated and for longer duration the tomato is kept fresh.