Question

What cellular changes occur during the differentiation of sieve elements that make them better adapted as food-conducting structures?

Answer 1

Sieve elements are cells of phloem which transport food across cells of the plant. There are two main types of sieve elements which are sieve cells and sieve tube members.

Sieve elements act as channels which transport sugars throughout the plant. Sieve elements contain elongated sieve areas on their walls. Pores present on these sieve areas allow for cytoplasmic connections to neighboring cells,allowing movement of photosynthetic and other organic molecules.

Formation ans differentiation :

Companion cells (cells assisting the activities of sieve elements) and sieve elements are formed from meristems. Meristems are living tissues which actively divide through a plant's life. .A series of formative and proliferative divisions take place in the meristem; these are followed by cell expansion and differentiation. The differentiation of protophloem is unique as it didferentiates at a distance of 20–25 cells away from the first stem cell. During the differentiation process the cells lose several organelles, including the nucleus, while the remaining organelles are rearranged.

Among the various events in the development of higher plants, there are two important processes that go hand in hand. One is growth , that is increase in size or volume and the other is differentiation; together it is called development. Growth is generally defined as an irreversible increase in size/volume accompanied with an increase in the protoplasmic mass. Differentiation, on the other hand, is a process in which new structures are formed with specific functions generating from the preexisting cellular components.Nevertheless these two events can occur together , meaning not mutually exclusive.