Question

Identify the incorrect statement about ABA growth regulator.
A. It increases the tolerance of plants against different stresses.
B. It acts as a general plant growth inhibitor and inhibitor of metabolism.
C. It helps in seed maturation and dormancy.
D. It promotes morphogenesis and differentiation of shoots.

Answer 1

Hint: The Abscisic acid hormone was first isolated and discovered by Carne and Adicott from cotton fruits. Years ago it was known as dormin and inhibitor B, later it was identified that both of them were the same substance. Abscisic acid is a somewhat acidic growth hormone which acts as a general growth inhibitor.

Complete answer:
The plant growth regulator hormone abscisic acid inhibits and stops the growth of plants. It acts antagonistically that is opposite to the growth-promoting hormones which include auxin, gibberellins, and cytokinins. It promotes dormancy and helps to overcome stressful conditions.
Now let us gather information about given options:-
It increases the tolerance of plants against different stresses. :- The concentration of ABA increases in the leaves of the plants during desiccation and other stressful conditions. As a result, stomata present in the epidermis of leaves close to prevent the loss of water i.e., transpiration.
It acts as a general plant growth inhibitor and inhibitor of metabolism. :- Abscisic acid inhibits gibberellin mediated amylase formation during germination of cereal grains and thus inhibits their sprouting.
It helps in seed maturation and dormancy. :- ABA acts as a growth inhibitor and induces dormancy of buds and seeds. As ABA induces dormancy, it is also known as dormin. The buds as well as seeds sprout only when ABA is overcome by gibberellins.
It promotes morphogenesis and differentiation of shoots. :- Cytokinins along with auxins are essential in tissue culture as they are required for cell division and morphogenesis/organogenesis. Thus ABA does not play any role in tissue culture.

Our required option is D that is It promotes morphogenesis and differentiation of shoots.

Note:
Application of minute quantity of ABA to leaves reduces transpiration to a great extent through partial closure of stomata. This hormone conserves water and lowers the requirement of irrigation. ABA is used to induce the dormancy of buds, seeds and storage organs. By inducing and promoting dormancy ABA helps the seed to withstand desiccation and other unfavourable factors.