Functions of Ethylene - Practice Questions & MCQ

1. Fruit Ripening: In climacteric fruits such as apples, bananas, tomatoes etc., exposure of mature fruits to ethylene result in respiration climacteric (marked increase in respiration during initiation of ripening) followed by additional production of ethylene leading to hastening of ripening process.

2. Transverse growth: Ethylene inhibits longitudinal growth but promotes the longitudinal growth.

3. Epinasty: When upper side (adaxial side) of the petiole of the leaf grows faster than the lower side (abaxial side), the leaf curves downward. This is called as epinasty. Ethylene causes leaf epinasty in tomato and other dicot plants such as potato, pea and sunflower. Young leaves are more sensitive than the older leaves. However, monocots do not exhibit this response.

4. Abscission of Leaves: Ethylene promotes abscission of leaves in plants. Older leaves are more sensitive than the younger ones.

5. Formation of Adventitious Roots and Root Hairs: Ethylene induces formation of adventitious roots in plants from different plant parts such as leaf, stem, peduncle and even other roots. Ethylene is known to inhibit linear growth of roots of dicotyledonous plants.

6. Sex expression: It promotes female flowers in cucumbers thereby increasing the yield

7. Triple Response: Ethylene causes ‘triple response’ of etiolated seedlings such as in pea which consists of:
(i) Inhibition of stem elongation,
(ii) Stimulation of radial swelling of stems and
(iii) Horizon­tal growth of stems with respect to gravity (i.e., diageotropism)

8. Flowering: Ethylene is used to initiate flowering and for synchronising fruit-set in pineapples. It also induces flowering in mango.