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Title: Determining the order of resistance genes against Stagonospora nodorum blotch, Fusarium head blight and stem rust on wheat chromosome 3BS

Author
item THAPA, RIMA - Purdue University
item Brown-Guedira, Gina
item OHM, HERBERT - Purdue University
item MATEOS-HERNANDEZ, MARIA - Purdue University
item WISE, KIERSTEN - Purdue University
item Goodwin, Stephen - Steve

Submitted to: BMC Research Notes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/13/2016
Publication Date: 2/2/2016
Citation: Thapa, R., Brown Guedira, G.L., Ohm, H.W., Mateos-Hernandez, M., Wise, K.A., Goodwin, S.B. 2016. Determining the order of resistance genes against Stagonospora nodorum blotch, Fusarium head blight and stem rust on wheat chromosome 3BS. BMC Research Notes. 9:58. doi: 10.1186/s13104-016-1859-z.

Interpretive Summary: Stagonospora nodorum blotch (SNB), Fusarium head blight (FHB) and stem rust (SR) are economically important diseases of wheat caused by the fungi Stagonospora nodorum, Fusarium graminearum and Puccinia graminis, respectively. These leaf and head diseases reduce grain yield and quality. FHB is very destructive due to production of a fungal toxin called vomitoxin that is harmful to both humans and livestock. Stem rust reduces plant vigor and can cause near 100% yield losses during severe epidemics. SNB affects both leaves and heads causing reduced yields with shrunken grain. Three genes conferring resistance to SNB, FHB and stem rust are closely linked on the short arm of wheat chromosome 3B. However, combining them together has been difficult because the order of the genes was not known. Based on previously published reports we developed a hypothesis that the gene order is FHB-SNB-SR. To test this hypothesis, 1,600 progeny plants from crosses between parental lines with resistance to these diseases were tested with molecular markers, and all of the progeny were tested for their resistance to SNB. Five molecular markers were used to make a genetic linkage map and determine the gene order. The results supported our hypothesis, indicating that the SNB resistance gene is located between the other two genes. Knowing the positional order of these fungal resistance genes will help plant breeders and pathologists to develop a wheat line with all three genes together to provide broad-spectrum resistance improving wheat quality and minimizing grain yield losses, and will help plant geneticists to try and clone the gene for SNB resistance.

Technical Abstract: Fungal diseases of wheat occur every year in the U.S., leading to significant grain yield losses. Stagonospora nodorum blotch (SNB), Fusarium head blight (FHB) and stem rust (SR) are caused by the fungi Stagonospora nodorum, Fusarium graminearum and Puccinia graminis, respectively. These leaf and head diseases reduce grain yield and quality. FHB is very destructive to wheat due to production of a mycotoxin that is harmful to both humans and livestock. SR reduces plant vigor and can cause near 100% yield losses during severe epidemics. SNB affects both leaves and heads causing reduced yields with shrunken grain. The most effective and economical means of controlling these diseases is the use of resistant cultivars. Three resistance factors, Qsng.sfr-3BS, Fhb1 and Sr2, conferring resistance to SNB, FHB and SR, are closely linked on the short arm of wheat chromosome 3B. Based on previously published reports our hypothesis was that Sr2 is the most distal, Fhb1 the most proximal and Qsng.sfr-3BS is in between Sr2 and Fhb1. To test this hypothesis, 1,600 F2 plants from crosses between parental lines Arina, Alsen and Ocoroni86 were screened with the parental lines using KASPar genotyping technology. Phenotypic screening for SNB was performed on all F2 plants. Five single-nucleotide polymorphism markers, Xsnp3BS-2, Xsnp3BS-3, g01130, Xumn10, and Xsnp3BS-9, were used to make the genetic linkage map, determine the gene order and for QTL analysis. The results supported our hypothesis, indicating that Qsng.sfr-3BS is located between the other two genes, and identified lines with two of the genes in coupling. Knowing the positional order of these fungal resistance genes will enable the development of a wheat line with all three genes in coupling to provide broad-spectrum resistance improving wheat quality and minimizing grain yield losses.