Somatic Hybridisation
உடல் செல் கலப்பினமாக்கல்
Sexual reproduction is limited by species barriers. Somatic hybridisation bypasses these barriers entirely. It is the surgical fusion of protoplasts, not gametes. Understand this, or you lose marks on plant breeding techniques.
The idea
Somatic hybridisation begins by isolating protoplasts from two different plant varieties using enzymes like cellulase and pectinase. These isolated protoplasts are fused using fusogens like Polyethylene Glycol (PEG) to form a hybrid protoplast. This hybrid protoplast is then cultured in a nutrient medium to regenerate into a new somatic hybrid plant. This process allows for the combination of desirable traits that are impossible to achieve through conventional hybridization.
Why it matters
It allows breeders to combine desirable traits from two different species that might not be sexually compatible.
NEET lens
NEET focuses on the agents used: Cellulase/Pectinase for cell wall digestion and PEG as the fusogen. Do not confuse somatic hybridisation with conventional breeding or protoplast culture. Memorise: Protoplast + Fusogen = Somatic Hybrid.
Clinical significance
In ecosystems, this technique mimics horizontal gene transfer, potentially creating plants with extreme stress resistance. If this process fails, the protoplasts undergo lysis or fail to regenerate, leading to a complete loss of the genetic material. It is the botanical equivalent of overcoming cellular incompatibility in tissue grafting.
Introduction
Somatic hybridisation is the fusion of protoplasts from two different varieties of plants, each having a desirable character, to produce a hybrid plant.
Core concept
Steps (NCERT): single cells are isolated from two plants; their cell walls are digested to obtain naked protoplasts surrounded by plasma membrane; isolated protoplasts from two different varieties (each having a desirable character) are fused to get hybrid protoplasts; the hybrid protoplasts are grown to form a new plant. These hybrids are called somatic hybrids. Example: a protoplast of tomato fused with that of potato grew into a new hybrid plant, the pomato, combining tomato and potato characteristics — however, it did not have all the desired combination of characteristics for commercial use. Polyethylene glycol (PEG) is commonly used to induce protoplast fusion.
Go deeper
Cell walls are removed with enzymes such as cellulase and pectinase, so that the plasma membranes of the two protoplasts can fuse.
From Class 10
Scientists can join cells of two different plants into one, and grow it into a new hybrid plant — like the 'pomato' from potato and tomato.