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Main activities
• Breeding program.
 
• Objectives.
• Traditional breeding scheme.
• Breeding at the diploid level.
• Maintenance of an IN VITRO germplasm bank.
• Seed potato producer.


     
  Breeding at the diploid level  
     
 

Potato is a tetraploid species and therefore classical breeding means the management of a great number of progenies. Breeding at the diploid level simplifies the selection and allow direct gene transfer from the wild and cultivated diploid Solanum species and thus, the broadening of the Program genetic base.

  
     
     
  1.- Dihaploid production.  
 

Diploid plants are achieved by crossing varieties or tetraploid breeding lines with Solanum phureja clones that induce the development of embryos without pollinization.

 
     
 

Dihaploids under field conditios (Valdelucio Valley).

Dihaploid clones are smaller and less vigorous than tetraploids.
 
 

 

  
 

IvP48, IvP35 e IvP101 S. phureja clones are used in dihaploid production. The embryo marker spot helps to distinguish seeds that are not diploid as the ones shown in the photograph.
 
 

 

  
     
  2.- Diploid progenies.  
 

More than 70% of the wild species are diploid and can be use in the creation of new diploid progenies. Some of the species used in these types of crosses are S. boliviense , S. chacoense , S. berthaultii , S. gourlayii , S. tarijense and S. vernei. They present resistance to biotic and abiotic stresses and quality features. The interespecific hybrids are backcrossed to recover the potato phenotype with the useful characteristic of the wild species.

 
     
 

Diploid clone with S. boliviense germplasm.

Diploid clone with S.gourlayi germplasm.
 
 

 

  
 

Diploid clone with S.berthaultii germplasm.

Diploid clone with S.chacoense germplasm.
 
 

 

  
 

 

  
  3.- Returning to the tetraploid level.  
 

The final step of a diploid breeding program is to recover the tetraploid level. Some diploid genotypes produce diplogametes (2n gametes) so they are crossed with tetraploid genotypes or diploid genotypes also producing 2n gametes to obtain tetraploid seeds.

 
     
 

2n pollen grains are bigger.

Tetrapoid clones obtaines by unilateral sexual polyploidization.
 
 

 

  
     
  4.- Somatic hybridization.  
 

Somatic hybridization by protoplast electrofusion is applied to return to the tetraploid level when diploid clones do not produce 2n gametes. Moreover, this technique is used to fusion wild species that cannot be sexually hybridized with diploid potato clones. These interspecific somatic hybrids can be used as parents in crosses with tetraploid genotypes to exploit the diversity of this wild germplasm.

 
     
 

Center: Somatic hybrid. Left and right: parentals. Somatic hybrid identification is carried out by DNA molecular markers and morphological evaluation.
Protoplasts (cells without cell wall).
 
Protoplasts aligment after AC application and fusions by DC pulse.
 
Calli culture and shoots growing.
 
 

 

  
  APPACALE Agrupación de Productores de patata de siembra de Castilla y León S.A. info@appacale.com Tel. 947 29 81 02 - Fax. 947 29 84 11 Burgos