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ARS Home » Midwest Area » St. Paul, Minnesota » Cereal Disease Lab » Research » Publications at this Location » Publication #302319
Title: Molecular mapping and validation of SrND643: a new wheat gene for resistance to the stem rust pathogen Ug99 race group

Author
item BASNET, BHOJA - International Maize & Wheat Improvement Center (CIMMYT)
item SINGH, SUKHWINDER - International Maize & Wheat Improvement Center (CIMMYT)
item LOPEZ-VERA, ERIC - International Maize & Wheat Improvement Center (CIMMYT)
item HUERTA-ESPINO, JULIO - Instituto Nacional De Investigaciones Forestales Y Agropecuarias (INIFAP)
item BHAVANI, SRIDHAR - International Maize & Wheat Improvement Center (CIMMYT)
item Jin, Yue
item Rouse, Matthew - Matt
item SINGH, RAVI - International Maize & Wheat Improvement Center (CIMMYT)

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/11/2014
Publication Date: 4/1/2015
Citation: Basnet, B.R., Singh, S., Lopez-Vera, E.E., Huerta-Espino, J., Bhavani, S., Jin, Y., Rouse, M.N., Singh, R.P. 2015. Molecular mapping and validation of SrND643: a new wheat gene for resistance to the stem rust pathogen Ug99 race group. Phytopathology. 105(4):470-476.

Interpretive Summary: Wheat stem rust, a disease caused by the fungus Puccinia graminis f. sp. tritici (Pgt), can result in severe yield losses in wheat. Large scale epidemics in several regions have been recorded. Recently stem rust races in the Ug99 race group with broad virulence have caused significant losses in eastern African. An advanced wheat breeding line ND643/2*Weebill1 carries a stem rust resistance gene, temporarily designated as SrND643, effective against Ug99 group of Pgt races at both seedling and adult growth stages. This study was conducted to map the chromosomal location of SrND643, and identify closely linked molecular markers to allow its selection in breeding populations. Genetic analyses located this gene at the distal end of chromosome 4AL. Closely linked molecular markers, Xgwm350 (0.5 cM), Xwmc219 (4.1 cM) and Xwmc776 (2.9 cM), were identified. The race specificity of SrND643 is different from those of Sr7a and Sr7b, two genes known to be present on chromosome 4AL, indicating that the resistance is conferred by a gene at a new locus or by a new allele of Sr7. The flanking markers Xgwm350 and Xwmc219 were predictive of the presence of SrND643 in advanced germplasm, thus validating the map location and their use in marker-assisted selection. This information will be useful for breeders to develop wheat cultivars for Ug99 resistance.

Technical Abstract: This study reports the identification of a new gene conferring resistance to Puccinia graminis f. sp. tritici (Pgt) race Ug99 in wheat (Triticum aestivum L.). Advanced wheat breeding line ND643/2*Weebill1 carries stem rust resistance gene, temporarily designated as SrND643, effective against Ug99 group of Pgt races at both seedling and adult growth stages. This study was conducted to map the chromosomal location of SrND643, and identify closely linked molecular markers to allow its selection in breeding populations. One hundred and forty eight recombinant inbred lines (RILs), developed by crossing ND643/2*Weebill1 with susceptible line Cacuke, were evaluated for stem rust response in field nurseries at Njoro, Kenya, during two growing seasons in 2010, and were genotyped with DNA markers including DArT, SSR and SNP. Linkage mapping tagged SrND643 at the distal end of chromosome 4AL showing close association with SSR markers Xgwm350 (0.5 cM), Xwmc219 (4.1 cM) and Xwmc776 (2.9 cM). The race specificity of SrND643 is different from those of Sr7a and Sr7b, indicating that the resistance is conferred by a gene at a new locus or by a new allele of Sr7. The flanking markers Xgwm350 and Xwmc219 were predictive of the presence of SrND643 in advanced germplasm, thus validating the map location and their use in marker-assisted selection.