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Doubling and DH production

Haploid plants are sterile. In order to produce seed on these plants, the genomes of cell lines developing into generative organs (tassel, ear) have to be initiated to double their genomes. This is usually done by applying a chemical, that interferes with cell division. At the DHF, we use colchicine for genome doubling. There are different methods to apply colchicine to haploid seedlings, they all have the goal to bring the cells of the basal meristem into close contact with the colchicine solution. We apply the chemical by injection at the 2-3 leaf stage.

injection scheme
Cross section of a young haploid seedling - in red basal meristems - indicating position of syringe for colchicine injection.
injection white plant
Injection of a chlorophyl mutant - the colchicine solution is colored with vegetable dye, for easier seeing the progress of injection

 

 

 

 

 

 

 

 

 

 

 

 

 

One to two days after treatment the seedlings are transplanted to the field.  At flowering time the haploid plants are screened on a daily basis for developing anthers. Fertility restoration is never complete, often only individual branches of a tassel show anthers with pollen shed. Usually the bottleneck in this process is the restoration of male fertility and depending on the population also the nick between available silk and pollen shed.