Validation of Molecular Markers for New Stem Rust Resistance Genes in U.S. Hard Winter Wheat

Abstract

Stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), is one of the most serious diseases of wheat (Triticum aestivum L.) worldwide. The discovery of new Pgt races in Africa, Ug99 and its variants, brings a new threat to global wheat production. Pyramiding several stem rust resistance genes into adapted varieties as opposed to breeding varieties with a single resistance gene is considered a more effective method to combat new races, but the success of gene pyramiding depends on the availability of molecular markers tightly linked to resistance genes. Markers for Ug99‐effective genes, Sr2, Sr22, Sr26, Sr32, Sr35, Sr39, and Sr40, were evaluated for usefulness in marker‐assisted selection (MAS) of hard winter wheat (HWW) using 10 resistance gene donor lines, 17 recently released U.S. HWW varieties or breeding lines, and 20 advanced introgression lines. Markers XcsIH81‐BM and XcsIH81‐AG for Sr22, Xsr26#43 and XBE51879 for Sr26, Xbarc55 for Sr32, Xbarc51 for Sr35, Xrwg27 for Sr39, Xsr39#22r for Sr40, and csSr2‐derived single nucleotide polymorphism (SNP) marker for Sr2 are diagnostic for the set of HWW accessions evaluated in this study. These markers should be useful in marker‐assisted pyramiding of stem rust resistance genes to develop HWW cultivars with multiple gene resistance against Ug99 races.

Molecular Markers Linked to Important Genes in Hard Winter Wheat

“…A set of 174 advanced winter wheat breeding lines from the USDA‐ARS‐coordinated Southern Regional Performance Nursery (SRPN) from 2008 to 2012 were screened with markers linked to various genes at the USDA‐ARS Central Small Grain Genotyping Laboratory, Manhattan, KS, following the protocol from Bernardo et al (2013) (Supplemental Table S3; Supplemental Fig. S2).…”

Registration of Near-Isogenic Winter Wheat Germplasm Contrasting in Fhb1 for Fusarium Head Blight Resistance

“…Polymerase chain reaction was performed in a PTC‐200 thermal cycler (Bio‐Rad Labs, Hercules, CA) using a touchdown program starting at 96°C for 5 min; followed by 5 cycles of 1 min at 96°C, 5 min at 68°C minus 2°C per cycle, and 1 min at 72°C; 5 cycles of 1 min at 96°C, 2 min at 58°C minus 2°C per cycle, and 1 min at 72°C; 25 cycles of 1 min at 96°C, 1 min at 50°C, and 1 min at 72°C; and a final extension of 5 min at 72°C. Primers labeled with FAM, VIC, NED, or PET (Life Technologies, Grand Island, NY) were run as described by Bernardo et al (2013). Fluorescent dye‐labeled PCR products were visualized on an ABI3730 sequencer (Life Technologies) and were scored using GeneMarker V1.5 (SoftGenetics, State College, PA).…”

Identification of Sr genes in new common wheat sources of resistance to stem rust race Ug99 using molecular markers

“…н.) (Dundas et al, 2007;Bernardo et al, 2013). Результаты анализа продуктов ПЦР по обо-им маркерам совпали.…”

“…Оба маркера идентифицировали Sr32 у контрольных линий C77.19.SR32 и CnsSr32AS, несущих транслокацию от Ae. speltoides в хромосоме 2B (McIntosh et al, 1995;Bernardo et al, 2013), а также у ана-лизируемых линий 119/4-06rw, 9/00w и сорта Донская полукарликовая.…”

“…Ген Sr40 был идентифицирован у линий 113/00i-4 и GT 96/90. Гены устойчивости Sr39 и Sr40 локализованы на хромосоме 2B, предполагается их сцепление (Bernardo et al, 2013). Те же авторы сообщили о том, что ампликон маркера Sr39#22 размером 820 п. н. диагностирует Sr40, в то время как фрагмент 818 п. н. диа-гностирует Sr39.…”