Effect of Nitric Oxide on Chlorophyll Content

Plastid is a membrane-bound cell organelle found only in plants, some algae, and some eukaryotic cells. Its function is mainly in photosynthesis and sometimes storage of metabolites. 

There are Three Types of Plastids, Namely:

1. Chloroplast: it is the type of plastid that contains a green-colored pigment called chlorophyll. It is associated with the process of photosynthesis.
2. Chromoplast: It is usually found in flowering plants, aging leaves, and fruits.
3. Leucoplast: these are colorless and generally found in non-photosynthetic parts of plants. It is mainly associated with storage and is of 3 types, namely:
   1. Amyloplast: amyloid refers to starch. It is mainly associated with the storage of starch which is the reserved food material of plants just like glycogen in animal cells.
   2. Proteinoplast: It serves for the storage of proteins.
   3. Elaioplast: It is associated with the storage of fats.

Chloroplast

Chloroplast is a cell organelle that contains chlorophyll that traps the photons of light and converts this light energy into chemical energy that drives the process of photosynthesis. It is found in all organisms performing photosynthesis. These organelles are found in the mesophyll cells of the plant leaves.

Chloroplast is a double membraned structure that contains grana which has stacks of thylakoid and stroma which is the homogenous matrix just like cytoplasm.

Chlorophyll

It is a green-colored pigment found in the mesosomes of cyanobacteria and chloroplasts of plants and algae.

All photosynthetic organisms use chlorophyll to trap sunlight photons and convert the absorbed light energy into chemical energy which further helps in the process of formation of carbohydrates as the food material.

Chlorophyll poorly absorbs the green color range of the light; it absorbs mainly blue light to perform photosynthesis.

Chlorophyll has a porphyrin ring and a central magnesium atom. This porphyrin ring participates in exciting electrons and their transfer.

A photon of light reaches a chlorophyll molecule, where it excites an electron. The energy given to the electron breaks the free atom present in the chlorophyll molecule.

The porphyrin binds with metal ions and performs different biological functions. Chlorophyll binds with magnesium to perform photosynthesis and is involved in the excitement of electrons.

Nitric oxide

Nitric oxide is a colorless gas and is represented as NO. It is the main signaling molecule in plant physiology. 

Nitric oxide production involves the reduction of nitrite by both enzymatic and non-enzymatic pathways. In the case of abiotic stress, it also acts as a bioactive signaling molecule. Its functions are:

• In antioxidant and reactive oxygen species response.
• Controls abiotic stress responses such as salt stress, drought stress, etc.
•  Preserve the level of chlorophyll in the dying leaves.

Effect of nitric oxide on chlorophyll content

As nitric oxide is a signaling molecule in plants, its alternative site is the chloroplast. Nitric oxide prevents the degradation of chlorophyll in the leaves undergoing senescence as the activities of chlorophyll catabolic enzymes are negatively regulated by nitric oxide. 

The deficiency of nitric oxide can cause a decrease in the photosynthetic complex stability inside the thylakoid membrane.

Nitric oxide is a negative regulator for catabolism but is positive for the thylakoid stability maintenance during leaf senescence.

The chlorophyll content will remain undisturbed in the case of the presence of nitric oxide in the dying leaves.

As the iron deficiency can block the chlorophyll synthesis and the development of chloroplast, nitric oxide helps in improving the iron availability in plants which will lead to proper biosynthesis of chlorophyll and chloroplast development.

Nitric oxide is a signal in gaseous form that helps in the modulation of growth, and stress tolerance in higher plants. NO treatment is used for boosting the endogenous NO level and results in proper growth and development of plants.

Conclusion

Thus, it is concluded that chlorophyll is present in the mesophyll cells of the leaves and is found in the chloroplast. Chloroplast is a plastid that is the main area of photosynthesis. Chlorophyll generally absorbs the photons of light of a particular wavelength which excites electrons and its energy is released. This energy is passed on from one chlorophyll molecule to another. This light energy is then converted to chemical energy which helps to drive the process of photosynthesis. Nitric oxide acts as a signaling molecule in plants. It is also involved in maintaining the growth, development, and stress tolerance in plants that make them adaptable to undergo any situation. Nitric oxide helps in the delay of degradation of the chlorophyll as it negatively regulates the catabolic enzymes of chlorophyll. No treatment is given to plants to boost their level of endogenous nitric oxide.