Pollen grains are formed by meiotic division of microspore mother cell. It contains half of the chromosome of parent cell. Parent plant cell (2n) has 28 chromosomes. Thus, pollen grain will have half the genetic content, that is 'n'. Therefore, it will have 14 chromosome.

Plant tissue culture is a process of growing plant cell in an artificial nutrient medium. The plant part in the media divides to form a mass of cell called callus. The cells leading to callus formation, divide mitotically. Hence, the number of chromosome in the cells of callus formed from pollen grain will have the same genetic content that is 14 chromosome.