Science behind DM11
- Mustard is a self-pollinating plant. (flowers contain both male and female organs).
- Therefore, a pollination control mechanism is required to encourage cross-pollination for hybrid seed production.
- For this, one of the two parental lines of a hybrid must be made male sterile so that it receives pollen from the other parent to form a seed.
- Male sterile lines can be developed using,
- cytoplasmic male sterility (CMS) (conventional breeding technique).
- Genetic engineering using transgenes.
- Examples of self-pollinating plants: Wheat, barley, oats, rice, tomatoes, potatoes, apricots, and peaches.
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- CMS systems have been found inadequate for large-scale hybrid seed production. Hence, there is a need to use Barnase-Barstar technology.
- Cytoplasmic male sterility (CMS) is a phenomenon in plants where a plant cannot produce functional pollen due to genetic factors in the cytoplasm rather than the nuclear genome.
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Barnase-barstar system
- It is a genetic engineering approach used in plants, particularly in crops like mustard, to achieve controlled male sterility and facilitate hybrid seed production.
- The technology utilises three genes derived from the soil bacterium Bacillus amyloliquefaciens (bar, barnase and barstar).
- In nature, bacterium excretes a defence protein called Barnase (ribonuclease), degrading competing bacteria’s RNA in an ecological niche.
- To protect itself from Barnase, the bacterium produces another protein called Barstar, which tightly binds with Barnase and renders it ineffective.
- The insertion of the Barnase gene in the mustard plant induces genetic male sterility by preventing the production of the male gametophytes (pollen grains).
- Meanwhile, the Barstar gene restores the plant’s ability to produce fertile hybrid seeds.
- The Bar gene is responsible for the Glufosinate (herbicide) resistance.
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