GrainGenes Reference Report: TAG-135-2627
Reference
TAG-135-2627
Title
Haplotype variants of Sr46 in Aegilops tauschii, the diploid D genome progenitor of wheat
Journal
Theoretical and Applied Genetics
Year
2022
Volume
135
Pages
2627-2639
Author
Athiyannan N
[ Show all 21 ]
Abstract
Key message. Stem rust resistance genes, SrRL5271 and Sr672.1 as well as SrCPI110651 , from Aegilops tauschii, the diploid D genome progenitor of wheat, are sequence variants of Sr46 differing by 1-2 nucleotides leading to non-synonymous amino acid substitutions. Abstract. The Aegilops tauschii (wheat D-genome progenitor) accessions RL 5271 and CPI110672 were identified as resistant to multiple races (including the Ug99) of the wheat stem rust pathogen Puccinia graminis f. sp. tritici (Pgt). This study was conducted to identify the stem rust resistance (Sr) gene(s) in both accessions. Genetic analysis of the resistance in RL 5271 identified a single dominant allele (SrRL5271) controlling resistance, whereas resistance segregated at two loci (SR672.1 and SR672.2) for a cross of CPI110672. Bulked segregant analysis placed SrRL5271 and Sr672.1 in a region on chromosome arm 2DS that encodes Sr46. Molecular marker screening, mapping and genomic sequence analysis demonstrated SrRL5271 and Sr672.1 are alleles of Sr46. The amino acid sequence of SrRL5271 and Sr672.1 is identical but differs from Sr46 (hereafter referred to as Sr46_h1 by following the gene nomenclature in wheat) by a single amino acid (N763K) and is thus designated Sr46_h2. Screening of a panel of Ae. tauschii accessions identified an additional allelic variant that differed from Sr46_h2 by a different amino acid (A648V) and was designated Sr46_h3. By contrast, the protein encoded by the susceptible allele of Ae. tauschii accession AL8/78 differed from these resistance proteins by 54 amino acid substitutions (94% nucleotide sequence gene identity). Cloning and complementation tests of the three resistance haplotypes confirmed their resistance to Pgt race 98-1,2,3,5,6 and partial resistance to Pgt race TTRTF in bread wheat. The three Sr46 haplotypes, with no virulent races detected yet, represent a valuable source for improving stem resistance in wheat.
External Databases
https://doi.org/10.1007/s00122-022-04132-w
Gene
Sr46 (Triticum)
Germplasm
Aegilops tauschii CPI110672
Locus
Sr46
Probe
Sr46
Sequence
Sr46_Diagnostic
GrainGenes is a product of the Agricultural Research Service of the US Department of Agriculture.
GrainGenes Reference Report: TAG-135-2627
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GrainGenes is a product of the Agricultural Research Service of the US Department of Agriculture. | |||