Question

Which of the following was first reported gibberellins to be discovered? (a) \(\mathrm{GA}_{1}\) (b) \(\mathrm{GA}_{2}\) (c) GA \(_{3}\) (d) \(\mathrm{GA}_{4}\)

Short answer

The first gibberellin to be discovered was GA \(_{3}\), so the correct answer is (c) GA \(_{3}\).

Step-by-step solution

Identify the Information Given

The gibberellins that we have to choose from are \(\mathrm{GA}_{1}\), \(\mathrm{GA}_{2}\), \(\mathrm{GA}_{3}\), and \(\mathrm{GA}_{4}\). The question wants to know which one was discovered first.

Research the Discovery of Gibberellins

To solve this, research is needed into the history of gibberellins' discovery. Gibberellins are a group of plant hormones that regulate growth and influence various developmental processes. These substances are named after the fungus Gibberella fujikuroi, the source of the first discovered gibberellin. Details gathered from research show that GA \(_{3}\) was the first gibberellin to be discovered.

Identify the Correct Answer

The first gibberellin to be discovered was GA \(_{3}\). Therefore, the correct answer is (c) GA \(_{3}\).

Key concepts

Plant Hormones

Plant hormones, also known as phytohormones, play a crucial role in the regulation of plant growth and development. Unlike animal hormones, plant hormones are not produced in specialized glands and may be produced by various parts of the plant, including stems, leaves, and roots. They move to where they're needed to stimulate reactions like cell division, flowering, seed growth, and leaf senescence.

Among the most well-known plant hormones are auxins, cytokinins, ethylene, abscisic acid, and gibberellins. Each has a unique function. For example, auxins are mainly involved in elongation of cells in shoots and are critical for the directional growth of plants in response to light and gravity. Gibberellins, on the other hand, are responsible for promoting cell elongation and division, stem elongation, and germination. The discovery and understanding of these hormones have been vital to many agricultural advances, allowing for the manipulation of plant processes to optimize crop yields and quality.

Gibberella fujikuroi

Gibberella fujikuroi is a fungus that has a historical significance in the field of botany and agriculture. It is the organism through which the first plant hormone of the gibberellins family was discovered. The fungus infects rice plants and causes a condition known as 'bakanae,' which means 'foolish seedling' in Japanese. This disease makes the infected rice plants grow uncontrollably tall and spindly, eventually leading to their death.

Scientists investigating this phenomenon in the early 20th century isolated a substance from the fungal culture that was responsible for this exaggerated growth. This was the discovery of gibberellins, which opened up a new era of research into plant growth and development. Understanding the effects of Gibberella fujikuroi and the gibberellins it produces has been pivotal for developing ways to enhance plant growth regulators, improve agricultural practices, and produce crop varieties with desirable traits.

GA3

Gibberellic acid, commonly referred to as GA₃, is the gibberellin with perhaps the most significant impact on agriculture. Discovered as the first gibberellin, it was identified in Gibberella fujikuroi cultures. GA₃ is a potent hormone that affects stem growth, seed germination, and fruit development in plants.

Its economic importance cannot be overstated, as it is widely used to promote the growth of seedless fruits like grapes, increase the malting of barley for beer production, and improve plant size and crop yields across a variety of plant species. From a scientific point of view, the discovery of GA₃ has led to vast research into the mechanisms of plant growth, providing insights that have been instrumental for the development of plant biotechnology and genetic engineering.