Function and evolution of allelic variation of Sr13 conferring resistance to stem rust in tetraploid wheat ( Triticum turgidum L.)

The Puccinia graminis f. sp. tritici (Pgt) Ug99 race group is virulent to most stem rust resistance genes currently deployed in wheat and poses a threat to global wheat production. The durum wheat (Triticum turgidum ssp. durum) gene Sr13 confers resistance to Ug99 and other virulent races, and is more effective at high temperatures. Using map-based cloning, we delimited a candidate region including two linked genes encoding coiled-coil nucleotide-binding leucine-rich repeat proteins designated CNL3 and CNL13. Three independent truncation mutations identified in each of these genes demonstrated that only CNL13 was required for Ug99 resistance. Transformation of an 8-kb genomic sequence including CNL13 into the susceptible wheat variety Fielder was sufficient to confer resistance to Ug99, confirming that CNL13 is Sr13. CNL13 transcripts were slightly down-regulated 2–6 days after Pgt inoculation and were not affected by temperature. By contrast, six pathogenesis-related (PR) genes were up-regulated at high temperatures only when both Sr13 and Pgt were present, suggesting that they may contribute to the high temperature resistance mechanism. We identified three Sr13-resistant haplotypes, which were present in one-third of cultivated emmer and durum wheats but absent in most tested common wheats (Triticum aestivum). These results suggest that Sr13 can be used to improve Ug99 resistance in a large proportion of modern wheat cultivars. To accelerate its deployment, we developed a diagnostic marker for Sr13. The identification of Sr13 expands the number of Pgt-resistance genes that can be incorporated into multigene transgenic cassettes to control this devastating disease.

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The inheritance of resistance to stem rust in 'K253', a hexaploid wheat with resistance from the tetraploid 'C.I. 7778'

Genome ◽

10.1139/g88-137 ◽

1988 ◽

Vol 30 (6) ◽

pp. 854-856

Author(s):

D. R. Knott

Keyword(s):

Triticum Aestivum ◽

Stem Rust ◽

Hexaploid Wheat ◽

Triticum Turgidum ◽

Dominant Gene ◽

Tetraploid Wheat ◽

Recessive Gene ◽

Triticum Aestivum L ◽

Puccinia Graminis ◽

Moderate Resistance

The inheritance of stem rust (Puccinia graminis f. sp. tritici Eriks. and Henn.) resistance was studied in 'K253', a hexaploid wheat (Triticum aestivum L.) with resistance derived from a tetraploid wheat (T. turgidum L.). The studies indicated that 'K253' carries one dominant gene for good resistance to races 29 and 56 (probably Sr9e) and one recessive gene for moderate resistance to race 15B-1. In addition, some plants apparently carry a recessive gene for moderate resistance to race 56. Four different types of hexaploid near-isogenic lines were produced. One carried Sr9e and another the gene for moderate resistance to race 15B-1. Two carried genes that had not been identified in the genetic studies, including one that was apparently not derived from K253.Key words: stem rust resistance, Puccinia graminis tritici, wheat, Triticum aestivum, Triticum turgidum.

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The Independent Domestication of Timopheev’s Wheat: Insights from Haplotype Analysis of the Brittle rachis 1 (BTR1-A) Gene

Genes ◽

10.3390/genes12030338 ◽

2021 ◽

Vol 12 (3) ◽

pp. 338

Author(s):

Moran Nave ◽

Mihriban Taş ◽

John Raupp ◽

Vijay K. Tiwari ◽

Hakan Ozkan ◽

...

Keyword(s):

Promoter Region ◽

Haplotype Analysis ◽

Common Ancestor ◽

Triticum Turgidum ◽

Tetraploid Wheat ◽

Wheat Species ◽

Loss Of Function ◽

Brittle Rachis ◽

Gene Level ◽

Large Panel

Triticum turgidum and T. timopheevii are two tetraploid wheat species sharing T. urartu as a common ancestor, and domesticated accessions from both of these allopolyploids exhibit nonbrittle rachis (i.e., nonshattering spikes). We previously described the loss-of-function mutations in the Brittle Rachis 1 genes BTR1-A and BTR1-B in the A and B subgenomes, respectively, that are responsible for this most visible domestication trait in T. turgidum. Resequencing of a large panel of wild and domesticated T. turgidum accessions subsequently led to the identification of the two progenitor haplotypes of the btr1-A and btr1-B domesticated alleles. Here, we extended the haplotype analysis to other T. turgidum subspecies and to the BTR1 homologues in the related T. timopheevii species. Our results showed that all the domesticated wheat subspecies within T. turgidum share common BTR1-A and BTR1-B haplotypes, confirming their common origin. In T. timopheevii, however, we identified a novel loss-of-function btr1-A allele underlying a partially brittle spike phenotype. This novel recessive allele appeared fixed within the pool of domesticated Timopheev’s wheat but was also carried by one wild timopheevii accession exhibiting partial brittleness. The promoter region for BTR1-B could not be amplified in any T. timopheevii accessions with any T. turgidum primer combination, exemplifying the gene-level distance between the two species. Altogether, our results support the concept of independent domestication processes for the two polyploid, wheat-related species.

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Field resistance to wheat stem rust in durum wheat ( Triticum turgidum ssp. durum ) accessions deposited at the USDA National Small Grains Collection

Crop Science ◽

10.1002/csc2.20466 ◽

2021 ◽

Author(s):

Pablo D. Olivera ◽

Worku D. Bulbula ◽

Ayele Badebo ◽

Harold E. Bockelman ◽

Erena A. Edae ◽

...

Keyword(s):

Durum Wheat ◽

Stem Rust ◽

Triticum Turgidum ◽

Field Resistance ◽

Wheat Stem Rust ◽

Small Grains

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Molecular characterization and chromosome-specific TRAP-marker development for Langdon durum D-genome disomic substitution lines

Genome ◽

10.1139/g06-114 ◽

2006 ◽

Vol 49 (12) ◽

pp. 1545-1554 ◽

Cited By ~ 17

Author(s):

J. Li ◽

D.L. Klindworth ◽

F. Shireen ◽

X. Cai ◽

J. Hu ◽

...

Keyword(s):

Triticum Turgidum ◽

Tetraploid Wheat ◽

Substitution Lines ◽

Genome Chromosome ◽

D Genome ◽

Single Chromosome ◽

B Genome ◽

The Individual ◽

Trap Marker

The aneuploid stocks of durum wheat ( Triticum turgidum L. subsp. durum (Desf.) Husnot) and common wheat ( T. aestivum L.) have been developed mainly in ‘Langdon’ (LDN) and ‘Chinese Spring’ (CS) cultivars, respectively. The LDN-CS D-genome chromosome disomic substitution (LDN-DS) lines, where a pair of CS D-genome chromosomes substitute for a corresponding homoeologous A- or B-genome chromosome pair of LDN, have been widely used to determine the chromosomal locations of genes in tetraploid wheat. The LDN-DS lines were originally developed by crossing CS nulli-tetrasomics with LDN, followed by 6 backcrosses with LDN. They have subsequently been improved with 5 additional backcrosses with LDN. The objectives of this study were to characterize a set of the 14 most recent LDN-DS lines and to develop chromosome-specific markers, using the newly developed TRAP (target region amplification polymorphism)-marker technique. A total of 307 polymorphic DNA fragments were amplified from LDN and CS, and 302 of them were assigned to individual chromosomes. Most of the markers (95.5%) were present on a single chromosome as chromosome-specific markers, but 4.5% of the markers mapped to 2 or more chromosomes. The number of markers per chromosome varied, from a low of 10 (chromosomes 1A and 6D) to a high of 24 (chromosome 3A). There was an average of 16.6, 16.6, and 15.9 markers per chromosome assigned to the A-, B-, and D-genome chromosomes, respectively, suggesting that TRAP markers were detected at a nearly equal frequency on the 3 genomes. A comparison of the source of the expressed sequence tags (ESTs), used to derive the fixed primers, with the chromosomal location of markers revealed that 15.5% of the TRAP markers were located on the same chromosomes as the ESTs used to generate the fixed primers. A fixed primer designed from an EST mapped on a chromosome or a homoeologous group amplified at least 1 fragment specific to that chromosome or group, suggesting that the fixed primers might generate markers from target regions. TRAP-marker analysis verified the retention of at least 13 pairs of A- or B-genome chromosomes from LDN and 1 pair of D-genome chromosomes from CS in each of the LDN-DS lines. The chromosome-specific markers developed in this study provide an identity for each of the chromosomes, and they will facilitate molecular and genetic characterization of the individual chromosomes, including genetic mapping and gene identification.

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Cytogenetic Studies in Ethiopian Landraces of Tetraploid Wheat (Triticum Turgidum L.) I. Spike Morphology vs Ploidy Level and Karyomorphology

Hereditas ◽

10.1111/j.1601-5223.1994.00045.x ◽

2004 ◽

Vol 121 (1) ◽

pp. 45-52 ◽

Cited By ~ 8

Author(s):

Getachew Belay ◽

Arnulf Merker ◽

Tesfaye Tesemma

Keyword(s):

Ploidy Level ◽

Triticum Turgidum ◽

Tetraploid Wheat ◽

Spike Morphology ◽

Cytogenetic Studies

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Molecular breeding for improving aluminium resistance in wheat.

Molecular breeding in wheat, maize and sorghum: strategies for improving abiotic stress tolerance and yield ◽

10.1079/9781789245431.0007 ◽

2021 ◽

pp. 116-145

Author(s):

Jorge Fernando Pereira

Keyword(s):

Triticum Turgidum ◽

Allelic Variation ◽

Resistance Mechanism ◽

Current Status ◽

Al Tolerance ◽

Resistant Lines ◽

Breeding Programmes ◽

Aluminium Resistance ◽

Wheat Wild Relatives ◽

Genomic Regions

Abstract This chapter aims at describing the main physiological mechanisms associated with aluminium (Al) resistance in wheat and how the research about these mechanisms has evolved to its current status. Practical aspects of phenotyping and using the molecular basis to increase Al resistance, which can be easily introduced in breeding programmes, are detailed. This chapter discusses the reliability of methods to screen root growth under Al stress, the allelic variation of genes associated with the main Al resistance mechanism in wheat, the quantitative trait loci and genomic regions that might contain minor Al tolerance genes, the use of wheat wild relatives, the uncertainties of developing transgenic wheat for greater Al resistance and the development of Al-resistant lines of durum wheat (Triticum turgidum subsp. durum).

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