Dictionary > Gerontoplast

Gerontoplast

Definition
noun, plural: gerontoplasts
A plastid that forms from chloroplast during senescence
Supplement
Plastids are organelles involved in the synthesis and storage of food. They are found within the cells of photosynthetic eukaryotes. In plants, plastids may develop into these forms: (1) chloroplasts, (2) chromoplasts, (3) gerontoplasts, and (4) leucoplasts.
Gerontoplasts are plastids that form from chloroplasts during senescence. Chloroplasts are plastids that have high amounts of green pigments (chlorophyll). They have a three membrane systems. These are the outer membrane, the inner membrane, and the thylakoid system. The thylakoid system is the site of the light-dependent reactions of photosynthesis. It is a stack of disks (granum) connected to another granum by stromal thylakoids.
The gerontoplast forms in a formerly green plant tissue that is undergoing senescence. During senescence of a leaf, the gerontoplast develops from chloroplast under genetic control. The gerontoplast is similar to the chromoplast in having a reduced thylakoid system and several plastoglobuli. However, it is unable to divide. The gerontoplast is capable of reverting to a chloroplast, however, for only up to a certain point. Once the cell enters the terminal phase of senescence, it will go through cell death and therefore the development of gerontoplast from chloroplast becomes irreversible.1
See also:

Reference(s):

1 Wise, R. & Hoober, J. (2007). The Structure and function of plastids. Dordrecht: Springer. p.433-ff.


You will also like...

Endemic Flora of New Zealand
New Zealand’s Unique Flora

If New Zealand has lots of unique animals, it's also got a whole lot of unique plants. Find out more about some of them,..

Psychiatry and mental disorders
Psychiatry & Mental Disorders

Different mental disorders are described here. Read this tutorial to get an overview of schizophrenia, affective mood di..

Ecological Research Measuring & Analysis
Ecological Research: Measuring & Analysis

This lesson is about the methods used for ecological research, such as quadrat and transect sampling, canopy fogging, an..

Adaptation Tutorial
Adaptation Tutorial

Adaptation, in biology and ecology, refers to the process or trait through which organisms or the populations in a habit..

Hominid
The Hominids

The hominid family diversified from the apes around 6 to 8 million years ago. Since then, the evolutionary path has prov..

Mātauranga Māori and Science Collaboration
Mātauranga Māori and Science

Mātauranga Māori is the living knowledge system of the indigenous people of New Zealand, including the relationships t..