Question

In a grafted plant, the stock has 48 chromosomes while the scion has 24 chromosomes. The chromosome number for the root cells and eggs are -
(a)48 and 24
(b)24 and 24
(c)24 and 12
(d)48 and 12

Answer 1

Hint: In plant grafting, the stock is the strong root part and the scion is the desired stem or flowering part. The stock cells have a constant number of chromosomes while the egg cells produced have half the number of the chromosomes of the scion.

Complete answer:
- Plant grafting is a technique in horticulture where tissues of different plants are joined together so they grow together.
- This technique is carried out in various plants for commercial and agricultural purposes.
- The single graft consists of the stock which is the root part of the plant that has the desired property, usually strength, and the scion, which is the stem part of the plant selected for the stem, fruits, leaves, and flowers.
- Since the scion bears the reproductive parts, the egg cells will have half the number of the chromosomes present in the scion.
- Hence, the stock has 48 chromosomes, the scion has 24 chromosomes (2n) and the eggs will have 12 chromosomes (n).

Additional Information: - Plant grafting is a method of asexual propagation.
- Based on the question, the endosperm of the plant will have 3n or 36 chromosomes.
- The zygote of the successfully grafted plant will have 2n or 24 chromosomes.

So, the correct answer is ‘48 and 12’.

Note: - For successful grafting, the vascular cambium tissues of the stock and scion plants must be placed in contact with each other and should be alive.
- Grafting confers various advantages to the plant such as pest resistance, extreme weather tolerance, and repair of damage of parts.
- Grafting of plants is also carried out for creating ornamental value.