What is heterosis
Heterosis, also known as hybrid vigor, refers to the phenomenon where the offspring (hybrid) of two different individuals exhibits superior characteristics compared to its parents in one or more aspects.
It's like having the "best of both worlds" from the parents, leading to enhanced traits like:
Increased size and growth rate.
Higher yield: This is important for crop production, leading to more fruits, vegetables, or grains.
Improved disease resistance: The hybrid might be better at fighting off infections compared to its parents.
Greater stress tolerance: This could involve resistance to drought, heat, or other environmental challenges.
Enhanced fertility: This can be beneficial for both plants and animals.
Dominance: Sometimes, one parent has "good" genes that mask the "bad" genes of the other parent, leading to a positive outcome in the offspring.
Overdominance: In some cases, the hybrid gets a beneficial effect from having different versions of the same gene from each parent, rather than just inheriting one dominant version.
Complementation: Different genes from each parent might work together to produce a better outcome than either parent could achieve alone.
Applications of heterosis
Agriculture: This is where heterosis is most widely used, with farmers cultivating hybrid crops for better yields and disease resistance.
Animal breeding: Crossing different breeds of animals can lead to offspring with improved meat production, milk yield, or disease resistance.
Aquaculture: Selective breeding of fish can also benefit from heterosis, leading to faster growth and higher survival rates.
Cabbage basic details
Cabbage (Brassica oleracea var capitata) is a small, leafy biennial producing a compact globular mass of smooth or crincled leaves wrapped over each other known as head.
The outer leaves are generally larger than the inner.
The stem is short and stout.
Plants flower generally after winter.
The males of plants as diverse as cabbage, cauliflower, broccoli, tomato, and rice can be made sterile by deleting a very small part of their genome’s DNA.
This is the take-home message of a paper published in the journal Nature Communications in October by researchers at the State Key Laboratory of Vegetable Biobreeding of the Chinese Academy of Agricultural Sciences, Beijing.
The simple deletion resulting in such a drastic outcome brings to mind the story of a kingdom that was lost for want of a horseshoe nail.
But here, instead of loss, the researchers assure us of a gain: that the deletion could lead to an abundant harvest of these plants, thanks to a process called heterosis.
Plant that couldn’t make pollen
Round 44 years ago, people found a cabbage plant that contained a natural mutation.
As a result of this mutation, they found that the plant had lost the ability to make pollen.
At first, scientists didn’t know which particular gene in the plant had been mutated.
They only named the altered gene, whichever it was, Ms-cd1.
The mutation’s effect was to make the plant male-sterile, but they had no other defects.
In fact, the eggs of the mutant plant could be fertilised by pollen from a normal plant, and the fertilised eggs would go on to make normal seeds.
In other words, all the seeds from the mutant plants were the result of the plants’ eggs being fertilised by pollen from plants of other strains – a process called out-crossing.
None of their seeds came from self-crossing. (In a self-cross, an egg is fertilised by pollen of the same strain.)
Out-cross seeds – which are also called hybrid seeds – germinate to produce more robust plants than self-cross seeds.
This is because of a phenomenon called hybrid vigour or, in technical terms, heterosis.
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