|KING, ZACHARY - University Of Georgia|
|CHILDS, SILAS - University Of Georgia|
|HARRIS, DONNA - University Of Georgia|
|BUCK, JAMES - University Of Georgia|
|BOERMA, H. ROGER - University Of Georgia|
|LI, ZENGLU - University Of Georgia|
Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/23/2017
Publication Date: 4/22/2017
Citation: King, Z.R., Childs, S.P., Harris, D.K., Pedley, K.F., Buck, J.W., Boerma, H., Li, Z. 2017. A new soybean rust resistance allele from PI 423972 at the Rpp4 locus. Molecular Breeding. 37:62.
Interpretive Summary: Asian soybean rust is an aggressive disease of soybeans that reduces yield. The disease was first reported in the United States (US) in 2004, and continues to be problem in the southern states of Alabama, Arkansas, Georgia, and Mississippi. The deployment of naturally occurring resistance genes is a preferred strategy for managing this disease, as they protect the plant from the disease without the need for fungicides. A new resistance gene, termed Rpp4-b, was characterized and mapped within the soybean genome. Rpp4-b provides resistance towards isolates of the pathogen present in the US, and has the potential to be a valuable resistance gene for soybean cultivar development in the southeastern US. Molecular markers and assays developed in this study offer a tool for soybean breeders to transfer the Rpp4-b gene into elite soybean germplasm.
Technical Abstract: Phakopsora pachyrhizi is a fungal pathogen and the cause of Asian soybean rust (SBR). P. pachyrhizi invaded the continental United States in 2004 and has since been a threat to the soybean industry. There are six described loci that harbor resistance to P. pachyrhizi (Rpp) genes. The resistance of PI 423972 was previously shown to be within 5 cM of the Rpp4 locus of PI 459025B, yet had differential reactions when challenged with the isolates India 1973 and Taiwan 1972. In this study, the resistance of PI 423972 was mapped to a 187.5 kb interval between the SNP markers GSM0543 and GSM0387 on Chromosome 18 (51,397,064 to 51,584,617 bp Glyma.Wm82.a2) that overlaps the interval for Rpp4 and is designated as Rpp4-b. A unique haplotype is described for PI 423972 that separates it from PI 459025B, 32 North American soybean ancestors, and all described sources of Rpp gene resistance.