pyramiding rust
TRANSCRIPT
Enhancing soybean rust resistance through Rpp2, Rpp3 and Rpp4 pair wise gene pyramiding
M. Maphosa, Talwana, H & Tukamuhabwa, P
Introduction
•Soybean rust is an obligate fungal parasite with multiple hosts
•It is a polycyclic disease with multiple re-infections
•Genetic resistance is a long term solution
•However, single genes have been overcome in certain areas whilst others show increasing susceptibility
•To enhance single gene resistance & broaden the base for available resistance genes
Introduction
•Conventional gene pyramiding is a challenge
•It is not practically feasible in some cases
•Marker assisted gene pyramiding may be a possible solution
•Given that some of the resistance genes have markers
associated with them
•No attempt has be done to use identified SSR for MAS
pyramiding & effect of pyramiding genes
Study 1
Marker Linkage Group Position1
(cM)
Resistance Gene Reference
Sat_255 J 43.85 Rpp2 Silva et al. (2008)
Satt620 J 53.71 Rpp2 Silva et al. (2008)
Satt460 C2 111.87 Rpp3 Hyten et al. (2009)
Sat263 C2 118.78 Rpp3 Hyten et al. (2009)
Satt288 G 76.77 Rpp4 Yamanaka et al. (2008)
AF162283 G 87.94 Rpp4 Yamanaka et al.(2008)
Study 2
•Evaluating the most effective resistance gene combination using sporulation & severity indices
Major Findings
• Complementary gene interactions occurred resulting in
enhanced resistance
• The effectiveness of resistance is influenced by the genetic
background of introgression
• Independent genetic control of severity and sporulation in
soybean rust
• Disproportinate contribution of resistance, Rpp3 more
dominant
Recommendations
• MAS gene pyramiding is feasible
• Introgression to elite lines
• Evalution of pairwise genes in other areas
• Assessing for durability of the resistance
Acknowledgements
•RUFORUM
•International Foundation for Science (4968-1)
•Makerere University Soybean breeding programme