Anther culture method: an overview
Did you know that you can grow plants in a tissue culture lab even from a pollen grain? There has been immense research in breeding where anther culture played a significant role. Let us today briefly talk about anther culture and different terms related to it!
In the plant science world, plants produced from anther or ovary culture are a critical source for studying the genetics of a certain plant species. Anther culture can help to produce a genetically identical population of plants for research on various agronomic characteristics. These studies help scientists to develop varieties that are more suitable for changing environmental conditions.
Apart from anther culture, there are some more interesting methods of tissue culture to obtain healthy in vitro plants. You can read more about them in our article on "7 methods of plant tissue culture".
What are haploid cells?
Haploid cells are single cells that contain genetic information from only one parent. In a plant, all plant parts have two cells and hence, they contain genetic information from both the male parent and the female parent. However, the flower carries parts that represent the male reproductive cells and the female reproductive cells. These cells possess genetic information from a single parent (male or female respectively).
Male haploid cells are called 'pollens' and female haploid cells are called 'ovule'. (See the diagram below for reference)
The process of embryo development starts when the pollen fuses with the ovule. You can call this process 'fertilization'. This embryo later develops into a seed and you can use this seed to grow a plant that represents both the parent plants.
Haploid cells are important as they represent only one parent and hence, can show characteristics of that parent. For example: plant height, flower color, yield, resistance to specific pest or disease, etc. can be studied from a specific plant using these cells. These genetic studies play a significant role in developing new varieties with improved resistance to a variety of pests or drought conditions.
What is haploid culture?
Haploid culture is one of the in vitro culture methods where you use haploid cells (pollens or ovules) to develop a whole plant.
In some plants, such as apples, this process occurs naturally and the phenomenon is known as 'parthenogenesis'. Here the embryo develops directly from an unfertilized egg. However, this is the only natural method that can lead to haploid plants.
When you develop plants using ovule from the flower, then it is known as ovary culture/gynogenesis. Production of plants using anthers is called anther culture/androgenesis. Haploid cultures are largely used by scientists to study plant mutations, identification of specific genes, development of hybrid varieties, etc.
What are anthers?
If you look inside a typical flower, you will see many small parts. In the diagram below, you can see the 'stamen' which is the male reproductive part, and the 'pistil' which is the female reproductive part. The anther is a part of the stamen that produces and stores pollen (they look like small powdery granules). There are hundreds of pollen in a flower. This pollen is meant to be dispersed from the anthers to different flowers in order to facilitate fertilization. This process is called cross-pollination and is crucial for developing hybrid varieties.
When you develop plants using complete anthers or individual pollens, then the process is known as anther culture. In this process, you provide a suitable environment for the pollens that they develop into complete plantlets without going through the fertilization process. Haploid production through anther culture is a two-way path that includes direct and indirect androgenesis. When pollens directly develop into an embryo and germinate under in vitro conditions to grow plantlets, then you can call this process 'direct androgenesis'. When pollens are induced to form a callus and this callus is further differentiated into a complete plant, then you can call this process 'indirect androgenesis'.
This method has been so successful that there are more than 100 plant species for whom a working anther culture protocol exists and it has been immensely successful for breeding and commercial use of japonica rice and crucial potato varieties.
What are haploid plants?
Haploid plants are viable plants that originated from pollen using tissue culture. In an easy language: these plants are generated using only one parent.
These plants did not have to undergo fertilization (crossing of an ovule and pollen), thus serving a major advantage in plant breeding research. In some cases, plants obtained from direct or indirect androgenesis generally achieve a normal set of chromosomes (genetics) like a traditionally fertilized plant with the help of a process called chromosome doubling.
There is one more type of haploid plant known as 'double haploid' where haploid cells undergo chromosome doubling. These haploids are popularly used in different breeding programs.
We will talk about them in detail in upcoming articles!
How are haploids useful in breeding?
Normal breeding experiments or programs take a long duration of time to develop a new variety or improve the already existing one. By long duration I mean 5 - 15 years, in some cases even 20 years. However, the production of these haploid plants reduces the time a breeder needs for several stages of crop improvement.
These reduce the breeding cycle by 2 – 6 years when compared with conventional breeding cycles. It also allows easy selection of agronomic characteristics for in-depth breeding research.
We hope you got a glimpse of different terms related to anther culture. For more informational posts on different aspects of haploid culture, keep checking this space!
Also if you like this article, do share it with others as well. Let us build a wonderful community of plant tissue culture enthusiasts.
By Nancy Bhatia | 02-September-2021
- Kyte, Kleyn, et al (2013) Plants from test tubes: An introduction to micropropagation. Timber press, Inc.
- Bhojwani, S.S., & Dantu, P.K. (2013). Plant Tissue Culture: An Introductory Text. Springer India
- Sharma, V., & Alam, A. (2015). Plant Tissue Culture. I.K. International Publishing House Pvt. Ltd.
- Robert H. Smith (2013). Plant Tissue Culture- Techniques and Experiments. Elsevier Inc.