Types of Senescence

Senescence, or cell aging, can occur in different types of cells, including melanocytes, endothelial cells, epithelial cells, glial cells, and stem cells. Various type of senescence are:

Senescence in Plants

Leaf senescence means the partial or complete death of the leaf. Senescence is the final stage of plant development and is a highly regulated program that recycles nutrients, mostly nitrogen, to the plant’s growing and storage organs. The senescence hormones regulates the process in plants. Some signs of senescence in plant include:

• The loss of chlorophyll, which causes leaves to turn yellow.
• Stoppage of the process of photosynthesis.
• Decrease in growth promoting hormone such as cytokinin and decrease in starch content.

Different type of senescence patterns observed in plants are:

• Overall Senescence: The entire plant is affected and undergoes senescence, leading to its death. Commonly seen in annual flowers and crops that complete their life cycle within a single growing season.
• Top Senescence: Affects only the above-ground parts of the plant. The underground parts, such as roots, may remain viable. Trees and shrubs that shed their leaves in autumn.
• Deciduous Senescence: It involves the senescence of all the leaves of the plant, in response to seasonal changes. It is less severe and occurs in deciduous trees, which lose their leaves in autumn as a part of the natural senescence process.
• Progressive Senescence: Innvolves the gradual progression of leaf senescence from the base upwards as the plant grows. Seen in some perennial plants where older leaves at the base of the plant senesce first, followed by the upper leaves as the plant continues to grow.

Replicative Senescence

This type of senescence occurs when telomeres shorten. It’s a physiological process that happens during aging. Replicative senescence involves an irreversible halt to cell proliferation and changes to cell function.

Stress-induced Senescence

Stress-induces senescence also known as stress-induced premature senescence (SIPS), regulates cell metabolism and function. It’s caused by oxidative stress to prevent cell growth. It occurs independently of a change in telomere length.

Developmental Senescence

Developmental senescence is a temporary, programmed cellular senescence that occurs during mammal’s embryonic development. It’s mediated by pathways or pluripotency genes. The role of developmental programmed senescence is to promote tissue remodeling.

Also Read: What Stem Cell is and its use?

Senescence is the process by which cells stop dividing and enter a state of permanent growth arrest without undergoing cell death. Senescence cells get old and weaken, causing a decline in tissue function and decay. Senescence in plants is a programmed death of leaves as part of developmental cycles. In animals, senescent cells contribute to aging and age-related diseases.

Senescence can be induced by unrepaired DNA damage or other cellular stresses. It plays a role in normal development, maintains tissue homeostasis, and limits tumor progression. In this article, we will read about what is senescence, its causes, and effects, senescent cells, the different types of senescence in plants, theories of aging, factors affecting senescence, and its importance.