16. In arum lily, the temperature of inflorescence rise around 10^°C as compare to plant during blooming. The natural trigger for heat production in the inflorescences of Saummatum guttatum (voodoo lily), a thermogenic plant, and identified it as salicylic add which allow expression of
(1) NADH Dehydrogenase                    (2) Cytochrome oxidase
(3) Alternate oxidase                        (4) Uncoupling protein

Introduction

Thermogenic plants like Saummatum guttatum (voodoo lily) exhibit a remarkable increase in inflorescence temperature during blooming, a process associated with facilitating pollination. The natural trigger for this heat production has been identified as salicylic acid, which induces the expression of specific proteins enabling alternative respiratory pathways.

Explanation of Each Option

(1) NADH dehydrogenase

• Involved in the initial electron transfer in mitochondria but not directly responsible for heat generation.

(2) Cytochrome oxidase

• Functions in the classical electron transport chain for ATP synthesis, not primarily involved in heat production.

(3) Alternate oxidase

• Correct. This protein is part of the alternative respiratory pathway that allows electron transport to continue without ATP synthesis, dissipating energy as heat, thus elevating inflorescence temperature.

(4) Uncoupling protein

• While uncoupling proteins dissipate proton gradients to generate heat in some organisms, in Saummatum guttatum, the alternate oxidase plays the primary role.

Why Alternate Oxidase Is Correct

Salicylic acid induces alternate oxidase expression in thermogenic plants, enabling a cyanide-resistant pathway. Electrons bypass complexes III and IV, reducing oxygen directly and releasing energy as heat rather than storing it as ATP.

This mechanism supports ecological strategies like attracting pollinators by heat generation.

Understanding this process is valuable for plant physiology, ecology, and metabolic regulation studies.