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GrainGenes Reference Report: TAG-103-1007

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Reference	TAG-103-1007
Title	An RGA-like marker detects all known Lr21 leaf rust resistance gene family members in Aegilops tauschii and wheat
Journal	Theoretical and Applied Genetics
Year	2001
Volume	103
Pages	1007-1013
Author	Huang L Gill BS
Abstract	Summary: Leaf rust is one of the most important diseases of wheat worldwide, particularly in the Great Plains region of the USA. One long-term strategy for the control of this disease may be through durable genetic resistance by gene pyramiding. An important step in this strategy is identifying molecular markers linked to different leaf rust-resistance genes. Here we report the molecular tagging of a leaf rust-resistance gene that may have the potential for durable resistance through further genetic manipulation and gene pyramiding. Lr39 was previously designated for a leaf rust-resistance gene introgressed from Aegilops tauschii accession TA1675 into the common wheat germplasm WGRC2. Lr40 was designated for a gene derived from Ae. tauschii accession TA1649 and is present in germplasm WGRC7. These genes are now believed to be allelic to Lr21, which was transferred to wheat from a different accession of Ae. tauschii. Molecular mapping of Lr39 and Lr40 indicates that both genes come from TA1649. WGRC2 and WRGC7 also have a similar infection type against rust culture PRTUS6. We suggest the designation of the gene in WGRC2 should be changed to Lr40. RFLP marker KSUD14 (locus Xksud14) was found 0.2-cM proximal to Lr40 in a WGRC2/Wichita F2 population (218 individuals), and co-segregated with the gene in a WGRC7/Wichita F2 population (165 individuals). A PCR-based molecular marker developed from the sequence-tagged-site (STS) of Xksud14 was mapped to the same locus as the RFLP marker KSUD14 in both populations. KSUD14 has the structure of a resistance gene analog (RGA) including kinase2a and kinase3 domains similar to the Cre3 gene of wheat and the rust resistance gene Rp1-D of maize. When the PCR products amplified from KSU14 STS were cleaved with restriction enzyme MspI, an 885-bp fragment was found in WGRC2, WGRC7, the Lr21 near-isogenic line, and eight accessions of Ae. tauschii shown to have resistance gene alleles at the Lr21 locus. The KSUD14 PCR-based assay provides an excellent marker for Lr40 and Lr21 in diverse wheat breeding and wild Ae. tauschii populations
Gene	Lr21 (Triticum)
2 Point Data	Lr21/XksuD14
Keyword	[ Hide all but 1 of 79 ] accessions aegilops aegilops tauschii allele assay barley breeding cloning cluster common common wheat culture disease disease resistance domain domains durable resistance enzyme f-2 population family family member fragment gene gene family gene pyramiding genetic genetic manipulation genetic resistance germplasm great-plains identification infection leaf leaf rust leaf rust resistance leaves line linkage locus long-term maize manipulation map mapping marker member molecular molecular mapping molecular marker near isogenic line pcr pcr products population product pyramiding region resistance resistance gene resistance gene analog restriction rflp rflp marker rga rust rust resistance rust resistance gene sequence-tagged-site strategy structure sts tauschii tomato triticum tauschii usa wheat wheat breeding wheat germplasm wild worldwide

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