7 Plant Cell Mitochondria Functions: Facts You Should Know


There are various organelles within a plant cell, among which Mitochondria is identified to have high significance as it is engaged in generating the major portion of the cellular energy to drive various functions within the cells. 

What is Mitochondria?

Mitochondria in the plant cells are membrane-bound organelles that help in producing a large portion of chemical energy which helps in facilitating different chemical reactions within the cells. Mitochondria forms a significant role in the survival process. 

Mitochondria is also recognised with the popular term, the “powerhouse” of the cells as they ensure the conversion of the food or glucose processed by plants through photosynthesis into a form of energy that would be effectively utilised by the cells and other components. 

The most important function of mitochondria is the production of energy to facilitate various biochemical reactions in the cells but there are other important functions as well. There are functions for signalling between cells, cell apoptosis and more.

plant cell mitochondria functions
Mitochondria from Pixabay

Mitochondria with own DNA 

Mitochondria is the organelle along with chloroplast within the cells of plants that have a unique genetic system identified as the mitochondrial DNA (mtDNA). The mtDNA is self-replicating in nature with a comparatively larger size than animals which have a diverse genome. 

Even though the major function of mitochondria is to produce energy for the cells, only 3% of the total number of genes are engaged in energy production. Majority of the genes in the mitochondrial DNA have been identified to be engaged in managing other types of functions. The functions are specific to cells. 

Since the mitochondrial DNA sizes for plant cells are large, the genres range from 50 to 60 in numbers based on the species. Only 13 of these genes engage in producing the enzymes to support the process of oxidative phosphorylation. 

The other genes are involved in managing other sets of activities like facilitating signalling between cells, cell apoptosis and more.  

Mitochondria in Producing Energy

The mitochondria are significant in disintegrating the glucose synthesised within the cells in order to generate adequate energy. Since plants are autotrophs, the food is produced through photosynthesis in chloroplast. The function of mitochondria is to produce energy through cellular respiration. 

In cellular respiration, oxygen and glucose is utilised by the cells to produce energy, water and carbon dioxide. Plants cells need to undergo cellular respiration at night to carry out all the functions of the cells. 

Cellular respiration starts within cytoplasm where glucose is converted into pyruvate through a process named glycolysis. Pyruvate is further converted to Acetyl-CoA which enters the mitochondrial matrix to enter Krebs cycle. 

A minimum amount of ATP is produced through glycolysis and Krebs cycle. The last step, oxidative phosphorylation, the electron carriers engage in donating the electrons within the electron transport chain occuring inside in the inner mitochondrial membrane. 

This further helps in producing ATP in large amounts through the hydrogen ion gradient using ATP synthase.

Mitochondria and Glycine oxidation

Photorespiration is identified as the process which gets initiated in the chloroplasts during CO2-fixing enzyme Rubisco reacts with O2 instead of reacting with CO2. Mitochondria along with peroxisomes has been engaged in salvaging the carbon that would leave the Calvin cycle in the form of the two-carbon compound known as the 2-phosphoglycolate. 

The formation of the two-carbon glycine is processed by amination within the peroxisomes followed by getting oxidised within the matrix of the plant mitochondria with the help of Glutaryl-CoA dehydrogenase (GCD). This process was discovered in the 1960s.

Mitochondria in Coenzyme transport and biosynthesis

Coenzymes are defined as small organic molecules that engage as enzyme cofactors important to facilitate enzymatic activity. Plants have the ability to synthesise all the important coenzymes that would be needed to function. 

The coenzymes that are synthesised are mostly used up in the metabolism of mitochondria and hence mitochondria engage in synthesising the coenzymes or have the ability to collect the coenzymes from the cytosol. 

Mitochondria and plant stress tolerance 

Alternative oxidase (AOX) is identified as one of the terminal oxidases produced by plant mitochondria through electron transport chain reactions. 

AOX aids in relaxing the highly coupled electron transport process within mitochondria which helps in maintaining the important metabolic homeostasis by helping to reduce oxygen to water. AOX in the entire process acts as a facilitator in signaling molecules to convey the metabolic status of mitochondria to the nucleus and in turn influence the nuclear gene expression. 

AOX is indirectly responsible for controlling the synthesis of signaling molecules like superoxide, hydrogen peroxide and nitric oxide, it helps in controlling the stress signalling and helps to manage stress situations in plants. 

Mitochondria in Heat production and thermoregulation

One of the most evident Alternative oxidase (AOX) functions has been identified to be heat production. The very high respiration rates that are caused by an increased density of mitochondria in combination with the AOX activities have the ability to drive up the temperature upto 20°C.  

This heating ability in plants helps in melting away the snow during cold and ensures the release of volatiles that would attract the carrion flies. In tropical areas, a heated flower chamber ensures a warm environment for mating. This helps in pollination. 

Mitochondria in Pathogen response

Mitochondria in plant cells have extended abilities to respond against any contamination caused by pathogens such as bacteria and fungi. Plant mitochondria have been identified as active sites for Reactive Oxygen Species (ROS) and NO production which are essential for pathogen defence.

The Mitochondria in plants tend to accumulate around the site of infection and display pathogen-induced redox imbalances to eliminate the pathogens.

Mitochondria in Apoptosis

Apoptosis is the process where the death of the cells occur in the body. This forms an important part in the span of life. Few cells over the span of time get old or damaged which need to be replenished with new series of cells. 

Mitochondria engage in playing an important role in replenishing with new cells by destroying the old ones. Mitochondria releases the important enzyme cytochrome C which is an important enzyme in activating another enzyme named “caspase” which facilitates the apoptosis process.

Conclusion

This can be concluded that there is a diverse set of plant cell mitochondria functions that helps in facilitating various processes like managing pathogens, arranging apoptosis, thermoregulation, stress tolerance, coenzyme transport, glycine oxidation and most importantly energy production.

Sayantani Misra

Hi, I am Sayantani Mishra, a science enthusiast trying to cope with the pace of scientific developments with a master’s degree in Biotechnology. Let's connect through LinkedIn-https://www.linkedin.com/mwlite/in/sayantani-misra-a54a83200

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