7 methods of plant tissue culture
Did you know that you can develop large number of plantlets using different methods of plant tissue culture?
For all the tissue culture enthusiasts out there, you can try different tissue culture methods for every plant species you work with. You can experiment as you wish and figure out on your own what works best for your plant of choice.
However, it is good to know that for certain plant species and varieties, only certain methods work. While for most plants, most of the methods would give the same end result. Your overall choice lies in your choice of explants and also how that particular kind of explant responds to tissue culture media!
Now that we are learning in depth about different aspects of plant tissue culture, it might be interesting for many of you to read about how you can set up your own lab? What equipment do you need? Where you need to be careful while planning? And so on! For more details you can have a look at our recent article on "How to set up a tissue culture laboratory?".
But for now, let us talk about different methods of developing plants using plant tissue culture:
The cool thing about plant tissue culture is that you can grow complete plants from any part of the plant, even with the seed. In this type of culture, you can use seeds directly to grow plants. These plants will be uniform and will grow much faster than in field conditions. This is also a good method when seeds have a hard outer coating and take quite longer to germinate in field conditions.
One common example of plant for which we can use seeds as explants is orchid!
Plants have interesting tissues at the top of a growing system known as meristem. These tissues have cells that do not have any specific function yet and we call them as meristematic cells. These cells have the ability to grow into any plant organ and perform the necessary functions related to it. Interesting, isn't it?
In plant tissue culture, we exploit this ability of meristematic cells to develop plant organs and later a whole functioning plant. Tissue culture using meristem tissues is called meristem culture.
Another interesting feature of meristem tissues is that they are free from viruses and other microorganisms. This feature helps us to get disease free plants using tissue culture. A lot of different plant species, for example, banana, can provide healthy plantlets using meristem culture.
Let us first understand what an embryo is! An embryo is an early form of plant life present in a seed. When we sow seeds in soil, it's the embryo that grows out and develop into a whole plant.
In tissue culture, we can use these embryos present in seeds as explants to grow viable plants. So the key here is to extract mature or immature embryos from seeds and supply them with necessary culture medium. This will lead to further development of shoot or root system of that plant. You can use immature seeds for gaining better insight into embryo development and seed maturation of plant species.
You can also tissue culture to develop plant embryos that otherwise might not survive to become viable plants. For instance, old seeds that are under storage for several years might not achieve decent germination in field conditions. So we can extract under developed embryos from these seeds and use tissue culture to develop them into plants. We call this method as embryo rescue. A lot of research is present on sweet corn using embryo rescue.
Callus is a growing mass of unorganized plant cells. This method is one of the common culture techniques. Here you extract few pieces of a tissue from any of the plant part and culture them on a suitable culture medium. The good thing about this kind of tissue culture is that it works for all the plant species!
The anther is actually the pollen bearing part of stamen. It is present in the male reproductive part of flower and contain pollen. These pollen represent the desirable set of genes and also the desirable characteristics. So when we use these pollen to produce plants using tissue culture, it is called anther culture.
One of the interesting facts about anther culture is that it produces haploid plants. So what are haploid plants?
In an easy language, haploid plants are plants that are generated using only one parent. These plants did not go through fertilization (crossing of an egg and a pollen), which is a time saving advantage. These plants achieve a normal set of chromosomes (genetics) like a traditionally fertilized plant with the help of a process called chromosome doubling. Breeders use this method often to develop hybrids in short duration of 2-3 years. Anther culture is a common tissue culture method for developing african violets and datura.
This method is an artificial process to develop an embryo from a single plant cell using specific culture media recipes for specific growth stages of embryo development. This embryo then later develops into a full plant. We call these embryos as somatic embryos because they are formed from plant cells that are not normally involved in the development of embryos.
This method is quite popular for plant species like coffee where other tissue culture methods do not perform well in regenerating plantlets. You can use this method in two ways: direct and indirect. In the direct way, you can develop media recipes by which the plant cells are developing into embryos directly. And in the indirect method, you need to prepare a different media recipe for each developmental stage.
Each plant cell has a rigid covering called cell wall. This cell wall makes it harder for any other element to enter the plant cell easily. When the cell wall is removed from a plant cell, it is called a protoplast. With protoplasts, it is easier for researchers to conduct cell studies and how biochemical reactions occur within a cell.
Plants like arabidopsis, rice, lettuce, tobacco, etc. are regularly cultivated using protoplast culture.
So these are the common methods to develop plants under in vitro conditions. We will be talking about each of these methods in detail in upcoming articles.
We hope these methods of plant tissue culture would be interesting for many of you. For more articles like these, keep checking our space!
By Nancy Bhatia | 02-June-2021
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