In tissue culture we can increase the efficiency of germination of seeds that are very difficult to germinate in vivo. Different plant growth regulators are used for premature germination of seeds in tissue culture. In tissue culture we can provide the environment to seeds that are optimum for germination and in this way also able to produce clean seedlings for explants or for meristem culture. Hence through controlled condition we can increase or decrease the rate of seed germination according to our requirement.
In tissue culture we can overcome embryo abortion which is caused by incompatible barriers. We can handle the self-sterility and dormancy of seeds. In tissue culture we can rescue embryo in distant (intergeneric or interspecific) hybridization where poor endosperm development occur in embryos. Shortening of breeding cycle in embryo also occur as a result of tissue culture technique which save times.
Ovary and ovule culture:
Production of haploids plants occur in tissue culture. A common explants can produce to initiate somatic embryogenic cultures. Overcoming abortion of embryos of wide hybrids at very early stages due to incompatibility barriers. In vitro fertilization to create distant hybrids prevent style and stigmatic incompatibility which inhibit pollen germination and pollen tube growth.
In vitro pollination:
We can produce hybrids which are difficult to produce through embryo rescue. In embryo rescue development of plant embryos occur that might not survive to become viable plants.
Anther and microspore culture:
In anther and microscopic culture we can produce haploid plants. We can produce homozygous diploid lines by chromosome doubling which minimize the time required to produce inbred lines.
Any part of a plant organ can use as an explants to initiate cultures.
Shoot apical meristem culture:
We can produce virus free germplasam. Mass production of our desirable genotype possible. Through cold storage we can conserve gemplasam in vitro.
This technique is major path of regeneration. Mass multiplication and production of artificial seeds occur. It also provide source material for embryogenic protoplasts.
This technique also serve as major path of regeneration and mass multiplication like somatic embryogenesis. We can conserve germplasam at normal or sub-zero temperatures through organogenesis.
Enhanced axillary budding:
In tissue culture through micropropagation we can enhance axillary budding production.
In some plants it is essential to go through a callus phase before regenerate through somatic embryo genesis or organogenesis. It is also useful to produce somaclonal variants which may be genetic or epigenetic.It provides a wide source of protoplasts, suspension cultures. We can also produce metabolites. This technique is use in in vitro selection.
In vitro mutagenesis:
We can induce polyploidy and also introduce genetic variability through this tissue culture technique.
Protoplast isolation, culture and fusion:
In this technique we combine genomes to produce somatic hybrids,cybrids and asymmetric hybrids.We can produce organelle recombinants and transfer of cytoplasmic male sterility occur.
In vitro flowering:
This technique can apply in some cases but no practical application found yet.
In this technique we can overcome graft incompatibility and development of virus free plants occur. When best part of young shoot or twig graft onto rootstock then rapid mass propagation occur in this way we get desirable traits like resistance to diseases and soil borne pathogens.
We can use many different explants depending on the type of plant species and use its favored method of regeneration and transformation according to plant species through this technique. We can introduce any desirable foreign DNA to generate novel genetic combinants.This method is also used to study the function of a particular gene.
Aqsa Tahir1, Asad Riaz2, Farah Kanwal3, Iqra Khalid4
1: All National Agriculture Research Council, Islamabad
2: All Center of Agriculture Biochemistry and Biotechnology
University of Agriculture, Faisalabad.