Organizing Committee


Poster Presentations


Poster Presentations


Mapping QTL for resistance to Asian soybean rust

Presenter: Nanda Chakraborty(1)

Other authors and affiliations: Joe Curley(1), Reid Frederick(2), Glen Hartman(3), Randall Nelson(3), Brian Diers(1). (1)University of Illinois Urbana-Champaign, Crop Sciences, Urbana, IL 61801, U.S.A.; (2)Foreign Disease-Weed Science Research Unit, USDA-ARS-NAA, Ft. Detrick, MD 21702-5023, U.S.A.; (3)USDA-ARS, University of Illinois, Crop Sciences, Urbana, IL 61801, U.S.A.

Asian soybean rust, caused by Phakopsora pachyrhizi, has potential to severely reduce soybean yields. Several major resistance genes are known but are specific to fungal strains and have been defeated. Therefore, identification of new resistance genes and partial resistance QTL is essential for breeding efforts against soybean rust. In our lab, recent efforts have involved two different mapping populations. One of the populations were derived from a plant introduction (PI) with resistant red-brown lesions, and the other was derived from a PI with a low number of susceptible tan lesions, suggesting partial resistance. These efforts have resulted in the mapping of what appears to be a different allele at Rpp1 from PI 594538A. We believe that this is a new allele because the resistance gene was mapped to the Rpp1 region from PI 594538A using a rust isolate, ZM01-1, that can overcome the original Rpp1 allele present in PI 200492. The other population was inoculated with a bulk pathogen population collected near Quincy, FL, in 2006. In that population, with PI 084674 as the resistant parent, there appeared to be segregation of reduced numbers of tan lesions. Using an SSR- and SNP-based linkage map, three QTL for lesion number were detected, on linkage groups A1, H, and K. The LOD scores ranged from 2.4 to 3.3, and the PI 084674 allele was associated with reduced lesion number.

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