Q.35 Which of the following acts as wound hormones in plants?
(A) Ethylene
(B) Cytokinins
(C) Abscisic acid
(D) Dextrin

Ethylene acts as the primary wound hormone among the given options in plants. This gaseous plant hormone is rapidly produced in response to mechanical injury, facilitating wound healing processes like suberization and defense responses. For CSIR NET Life Sciences preparation, understanding its role distinguishes it from other options.​

Option Analysis

(A) Ethylene: Correct. Wounding triggers ethylene biosynthesis from methionine via ACC synthase, leading to responses such as suberization in potato tubers and stem healing. It works alongside jasmonate but is directly linked to injury sites.​

(B) Cytokinins: Incorrect. These promote cell division, shoot formation, and delay senescence but lack a primary role in wound signaling or healing.​

(C) Abscisic acid: Incorrect. Known as a stress hormone for stomatal closure and dormancy, it participates in broader wound signaling but not as the main wound hormone.​

(D) Dextrin: Incorrect. A starch derivative involved in general carbohydrate metabolism, not hormone action or wound-specific responses in plants.​

Plants face constant threats from herbivores, mechanical damage, and pathogens, relying on wound hormones in plants like ethylene to initiate rapid healing. Ethylene, a gaseous phytohormone, surges post-injury to trigger suberization, callus formation, and defense gene expression, making it essential for survival.​

Ethylene: Primary Wound Hormone

Ethylene production peaks 2-3 days after wounding via the ACC pathway, promoting periderm regeneration and gas diffusion changes that signal repair. Recent studies highlight its role in oxygen influx and ethylene escape at wound sites.​

• Accelerates suberization in tubers.​

• Induces adventitious roots and abscission.​

• Interacts with jasmonate for systemic signaling.​

Other Hormones’ Limited Roles

Cytokinins focus on growth promotion, abscisic acid on drought stress, while dextrin serves metabolic functions without hormonal wound activity.​