Presentation Transcript
Slide 1:Pyramiding of genes Backcross 1 Backcross 2 Backcross 3 Backcross 4 Gene 1 Gene 2 Gene 3 Gene 4 Variety A x
Source 1 source 2 source 3 source 4 6-8 years x x Variety A 1+2 Variety A 3+4 6-8 years x Variety A 1+2+3+4 6-8 years Time consuming, sanctity of variety may be lost, new varieties would come MULTIPLE RESISTANT VARIETY
Slide 2:Backcross 1 Backcross 2 Backcross 3 Backcross 4 Gene 1 Gene 2 Gene 3 Gene 4 HHB 67 x Downy mildew resistant races
Race 1 Race 2 Race 3 Race 4 6-8 years x x HHB 67-1 HHB 67-2 6-8 years Example: HHB 67 (Pearlmillet hybrid) Time reduced to 2-3 years Used MAS approach Version 1 Version 2
Slide 3:Backcross 1 Backcross 2 Backcross 3 Backcross 4 Gene 1 Gene 2 Gene 3 Gene 4 Variety A x
Source 1 source 2 source 3 source 4 6-8 years MULTILINE VARIETY
Mixture of many pure lines Clean crop approach
Slide 4:Variety A x
Source 1 source 2 source 3 source 4 DIRTY crop approach MULTILINE VARIETY
Mixture of many pure lines
Slide 5:EXAMPLES (Multiline varieties): important where new races of diseases are continuously developed
three multiline varieties have been released in India in wheat
Kalyansona was used as a recurrent parent in all these varieties KSML 3 8 lines
MLKS 11 8 lines
KML 7406 9 lines Robin, Ghanate, K1, Rend, Gabato, Blue bird, Tobari etc. E 6254, E 6056, E 5868, Frecor, HS 19, E 4894, etc. Wheat Rust Resistant Varieties INDIA USA Miramar wheat
Oat multiline variety
Slide 6:Breeding strategy for tolerance Breeding for tolerance is similar to breeding for horizontal resistance