|Vuong, Tri - University Of Missouri|
|Nguyen, Binh - Plant Protection Research Institute - Vietnam|
|Nguyen, Tuyet - Plant Protection Research Institute - Vietnam|
|Dinh, Hoan - Plant Protection Research Institute - Vietnam|
|Hyten, David - University Of Nebraska|
|Sleper, David - University Of Missouri|
|Lee, Jeong - Kyungpook National University|
|Shannon, John - University Of Missouri|
|Nguyen, Henry - University Of Missouri|
Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/26/2016
Publication Date: 12/9/2016
Citation: Vuong, T.D., Walker, D.R., Nguyen, B.T., Nguyen, T.T., Dinh, H.X., Hyten, D.L., Cregan, P.B., Sleper, D.A., Lee, J.D., Shannon, J.G., Nguyen, H.T. 2016. Molecular characterization of resistance to soybean rust (Phakopsora pachyrhizi Syd. & Syd.) in soybean cultivar DT 2000 (PI 635999). PLoS One. 11(12)e0164493. doi:10.1371/journal.pone.0164493.
Interpretive Summary: Soybean rust caused by Phakopsora pachyrhizi has the potential to cause up to 80% yield losses on soybean in the tropics and is a threat to soybean grown in the southern United States, so resistant cultivars are needed. DT 2000 is a rust-resistant cultivar from Vietnam which also has resistance in the USA. Through the use of several different molecular mapping methods and disease reaction data collected in Florida and in Ha Noi, Vietnam, DT 2000 was found to carry two different rust resistance (Rpp) genes. One at the Rpp3 locus on soybean Chromosome 6 was associated with disease levels in both locations. A gene at the Rpp4 locus on on Chromosome 18 was associated with disease variation only in Vietnam, but might provide resistance to other rust strains in the USA. The identification of the two independent genes and SNP and SSR markers tightly linked to them will make it easier for U.S. soybean breeders to transfer those genes into high-yielding, susceptible soybean lines. If these genes prove to be diffferent from previously characterzed genes, they will be of particulat value for diversification of the Rpp genes available to U.S. soybean breeders for developing rust-resistant cultivars, and can be combined with Rpp genes at other loci to increase the breadth and durability of rust resistance.
Technical Abstract: Resistance to soybean rust (SBR), caused by Phakopsora pachyrhizi Syd.& Syd., has been identified in many soybean germplasm accessions and is conferred by either dominant or recessive genes that have been mapped to six independent loci (Rpp1 – Rpp6), but No U.S. cultivars are resistant to SBR. The cultivar DT 2000 (PI 635999) has resistance to P. pachyrhizi isolates and field populations from the United States as well as Vietnam. A F6:7 recombinant inbred line (RIL) population derived from Williams 82 × DT 2000 was used to identify genomic regions associated with resistance to SBR in the field in Ha Noi, Vietnam, and in Quincy, Florida, in 2008. Bulked segregant analysis (BSA) was conducted using the soybean single nucleotide polymorphism (SNP) USLP 1.0 panel along with simple sequence repeat (SSR) markers to detect regions of the genome associated with resistance. BSA identified four BARC_SNP markers near the Rpp3 locus on chromosome (Chr.) 6. Genetic analysis identified an additional genomic region around the Rpp4 locus on Chr. 18 that was significantly associated with variation in area under disease progress curve (AUDPC) values and sporulation in Vietnam. Molecular markers tightly linked to the DT 2000 resistance alleles on Chrs. 6 and 18 will be useful for marker-assisted selection and backcrossing in order to pyramid these genes with other available SBR resistance genes to develop new varieties with enhanced and durable resistance to SBR.