Polyploidy is induced through:

✅Explanation:
Polyploidy is a condition in which an organism has more than two sets of chromosomes. This can occur naturally, but it can also be induced artificially through various methods.
● Colchicine: This is a plant-derived chemical that disrupts cell division, preventing the spindle fibers from forming properly. This can lead to the duplication of chromosomes without cell division, resulting in a polyploid cell.
● Irradiation: High doses of radiation can damage chromosomes, sometimes leading to breaks and rearrangements. In rare cases, this can result in polyploidy. However, irradiation is not a commonly used method for inducing polyploidy because it can have other harmful effects on the organism.
● Mutagenic chemicals: These are chemicals that can cause mutations in DNA. While some mutations can lead to polyploidy, this is not a specific effect of most mutagens and is not a reliable method for inducing polyploidy.
● Ethylene: This is a plant hormone that can regulate various developmental processes. While it can affect cell division in some cases, it is not known to induce polyploidy specifically.

🔑IMP Key Points:
• Poly means ''many'' and ploidy means '' haploid set of chromosomes'' so when a cell has three o sets of chromosomes then that condition is called polyploidy.
• Polyploidy in a cell can be induced by several methods like Colchine treatment, Heat or cold shock, and centrifugation.

• Polyploidy is of two types:
1. Autopolyploidy – It is the repetition of the same set of chromosomes. Eg – BBB
2. Allopolyploidy – Increase in both the types of genomes of a hybrid plant, formed from two different species. Using allopolyploidy new plant species can be formed.

✅Explanation:
• Colchicine is the most widely used to induce polyploidy in plants, It suppresses the mitotic spindle fiber formation, causing non-segregation of chromosomes due to which doubling of chromosomes occurs.

• Use of Colchicine in plant breeding:
• Raphanobrassica (2n = 18) is obtained by crossing Raphanus sativus (2n = 18) and Brassica oleracea (2n = 18), which is a sterile plant, but after the application of colchicine the chromosome number doubles up and fertile Raphanabrassica (4n = 36) is formed.
• Polyploidy helps in evading inbreeding depression.
Additional Information
• Formalin: 30-40% aqueous solution of the formaldehyde is known as formalin. It is a biological preservative used for storing dead organisms.
• 5-Bromouracil is a brominated derivative of uracil that acts as an antimetabolite or base analog, substituting for thymine in DNA, and can induce DNA mutation in the same way as 2-aminopurine