Give a brief account on Programmed Cell Death (PCD).

Explanation

Senescence is controlled by plants own genetic programme and death of the plant or plant part consequent to sentances is called Programmed Cell Death. In short senescence of an individual cell is called PCD. The proteolytic enzymen involving PCD in plants are phytaspases and in animal are caspases. The nutrients and other substrates from senescing cells and tissue are remobilized and reallocated to other parts of the plant that survives. The protoplasts of developing xylem vessel and tracheids die and disappear at maturity to make them functionally efficient to conduct water for transport. In aquatic plants, aerenchyma is norlammy formed in different parts of the plant such as roots and stems which encloses large air spaces that are created through PCD. In the development of unisexual flowers, male and female flowers are present in earlier stages, but only one of these two completes its development while other abourts through PCD.