Plastid inheritance in mirabilis

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 Plastid Inheritance in mirabilis

The extra nuclear Or cytoplasmic inheritance of colour in plants plastids* was first discovered by Correns in Mirabils jalapa. 
Mirabilis jalapa plant can bear 3types of branches  i.e. green, variegated and pale (or white). 
Correns found that :
  1. The flowers on green branches produced plants only with green leaves irrespective of genotype or phenotype of pollen parent,
  2. The flower on pale branches produced only pale plants regardless of genotype or phenotype of pollen parent.
  3. Flowers of variegated branches formed seeds which give rise to 3types of plants : green, pale, variegated. 

The type of branch giving pollen grains hardly matters for this type of inheritance. This is due to random distribution of green and colorless Plastid at the time of female gamete formation. 

*Plastid : These are semi -autonomous organelle which have their own DNA, replication, transcription and translation machinery. Three types of Plastid can be identified : Chloroplasts (green Plastid),  Chromoplasts (colored Plastid)  ,leucoplasts(colorless Plastid). 



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