Question

Lettuce hypocotyls elongation is performed for bioassay of?
A) Gibberellin
B) Ethylene
C) Cytokinin
D) ABA

Answer 1

Hint:Gibberellin, auxin, cytokinin, and ABA (Abscisic) are plant hormones produced within the plants that are present in very low concentrations. They control a lot of plant aspects of plant growth like pathogen defense, stress tolerance, embryogenesis, etc.

Complete answer:
Excised lettuce (Lactuca sativa L.) hypocotyl sections maintain the ability to elongate in response to gibberellic acid (GA(3)) addition. In 48 hours at 30⁰C a GA(3) treated segment is more than doubled, at the same time as a control segment elongates less than 50%. Auxin has no noticeable effect on this system. Compassion to GA(3) is not decreased by apex or root elimination. Stress-relaxation examination of the mechanical properties of the lettuce hypocotyl cell wall established that gibberellic acid caused cell wall loosening and dihydro coniferyl alcohol and pestalotia did not influence this gibberellin effect.
Gibberellins (GAs) are plant hormones that control various developmental processes, as well as stem elongation, germination, dormancy, flowering, flower development, and leaf and fruit senescence. GAs are one of the best-known classes of plant hormone. It is considered that the selective breeding of crop strains that were lacking in GA synthesis was one of the key drivers of the green revolution in the 1960s, a revolution that is attributed to have saved over a billion lives worldwide.

Hence the correct answer to this question is the option (A) gibberellin.

Note:Gibberellins help in the cell elongation of the excised hypocotyls of lettuce. Elongation of these sections incubated in the light is inhibited when compared to the dark-grown sections. This inhibition is reversed by gibberellic acid (GA3).