Afficher la couverture 'Using virulence mutants to identify Avr genes in the wheat stem rust fungus, Puccinia graminis f. sp. tritici. 30th Fungal Genetics Conference. | Ortiz-Vallejo, Diana' en grand format
/5

0 avis

Using virulence mutants to identify Avr genes in the wheat stem rust fungus, Puccinia graminis f. sp. tritici. 30th Fungal Genetics Conference.

Archive ouverte

Ortiz-Vallejo, Diana | Upadhyaya, Narayana, M | Chen, Jian | Luo, Ming | Park, Richard | Figueroa, Melania

Edité par CCSD -

International audience. The wheat stem rust fungus Puccinia graminis f. sp. tritici (Pgt) is one of the mostdestructive pathogens of wheat. Resistance of host lines is often governed by recognition of fungal effectorproteins (avirulence/virulence proteins) by plant resistance proteins (R proteins). We have taken amutational genomics approach to identify Avr genes in Pgt. We isolated spontaneous mutants withvirulence for Sr50, Sr5, Sr27, Sr21 or Sr45 by selection on resistant host lines. Sequence analysis of theSr50 virulent mutant revealed that virulence resulted from the exchange of a whole chromosome betweenthe two haploid nuclei of this dikaryotic organism, resulting in loss of the avirulence allele. This confirms theimportant role of somatic exchange events in virulence evolution in Pgt. The AvrSr50 gene was identifiedfrom the 25 candidate effector genes from this chromosome by transient co-expression with the clonedSr50 gene in N. benthamiana. AvrSr50 recognition was confirmed in wheat by viral expression. Recognitionof the AvrSr50 protein by the host Sr50 immune receptor is based on direct interaction and we haveidentified critical amino acid polymorphisms contributing to the escape from recognition in virulent isolates.Identification of AvrSr50 has enabled development of tools for testing effector function in wheat includingviral overexpression and wheat protoplast transient expression assays. Spontaneous mutants for severalother Avr loci have also been sequenced and a new Pacbio-based genome assembly for the Australianparental Pgt isolate has facilitated the delineation of these loci. Three mutants with virulence for Sr27contain overlapping deletions and a single candidate gene for AvrSr27 has been identified. Likewise,AvrSr5 mutants contain large deletions spanning several candidate effector genes.

Consulter en ligne

Suggestions

Du même auteur

Genomics accelerated isolation of a new stem rust avirulence gene–wheat resistance gene pair

Archive ouverte | Upadhyaya, Narayana, M | CCSD

International audience. Stem rust caused by the fungus Puccinia graminis f. sp. tritici (Pgt) is a devastating disease of the global staple crop wheat. Although this disease was largely controlled in the latter half...

Genomics accelerated isolation of a new stem rust avirulence gene–wheat resistance gene pair

Archive ouverte | Upadhyaya, Narayana | CCSD

International audience. Stem rust caused by the fungus Puccinia graminis f. sp. tritici (Pgt) is a devastating disease of the global staple crop wheat. Although this disease was largely controlled in the latter half...

A five-transgene cassette confers broad-spectrum resistance to a fungal rust pathogen in wheat

Archive ouverte | Luo, Ming | CCSD

International audience. Breeding wheat with durable resistance to the fungal pathogen Puccinia graminis f. sp. tritici (Pgt), a major threat to cereal production, is challenging due to the rapid evolution of pathoge...

Chargement des enrichissements...