Virulence and Molecular Analyses Support Asexual Reproduction of <i>Puccinia striiformis</i> f. sp. <i>tritici</i> in the U.S. Pacific Northwest

Peng, Cheng; Chen, X M

doi:10.1094/phyto-11-13-0314-r

Cited by 40 publications

(24 citation statements)

References 55 publications

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“…In the present study, high telia production may be explained by two hypotheses: one is the possibility of sexuality in the Pst population in some parts of Canada, which is possible because common barberry exists in the province of Ontario (Tom Fetch, personal communication) and it might exist in the province of British Columbia, which is close to the PNW of the USA, where barberry is reported (Cheng and Chen, ). In Canada, the existence of common barberry (an alternate host for the oat stem rust fungus) has resulted in oat stem rust races that form telia faster and produce more telia as compared to clonal races (T. Fetch, pers.…”

Section: Discussionmentioning

confidence: 72%

Genome re‐sequencing and simple sequence repeat markers reveal the existence of divergent lineages in the Canadian Puccinia striiformis f. sp. tritici population with extensive DNA methylation

Brar

Ali

Qutob³

et al. 2018

Environmental Microbiology

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Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is an important disease in Canada. The worldwide genetic structure of Pst populations have been characterized, excluding Canada. Here, we elucidated the genetic structure of the western Canadian Pst population using molecular markers, revealing the presence of four divergent lineages with predominantly clonal structure. In the worldwide context, two previously reported lineages were identified: PstS0 (22%), representing an old Northwestern-European and PstS1 (35%), an invasive warm-temperature adapted. Additionally, two new, unreported lineages, PstPr (9%) and PstS1-related (35%), were detected, which produced more telia than other lineages and had double the number of unique recombination events. The PstPr was a recent invasion, and likely evolved in a diverse, recombinant population as it was closely related to the PstS5, PstS7/Warrior, PstS8/Kranich, and PstS9 lineages originating from sexually recombining populations in the centre of diversity. The DNA methylation analysis revealed DNA-methyltransferase1-homologs, providing compelling evidence for epigenetic regulation and as a first report, an average of ∼5%, 5hmC in the Puccinia epigenome merits further investigation. The divergent lineages in the Canadian Pst population with the potential for genetic recombination, as well as epigenetic regulation needs consideration in the context of pathogen adaptation and management.

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Section: Discussionmentioning

confidence: 72%

Genome re‐sequencing and simple sequence repeat markers reveal the existence of divergent lineages in the Canadian Puccinia striiformis f. sp. tritici population with extensive DNA methylation

Brar

Ali

Qutob³

et al. 2018

Environmental Microbiology

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“…This can be explained by the property of Pst and EMS mutagenesis. i) The two nuclei in Pst urediniospores were found to be highly heterozygous in many isolates [37,39,58,59]. ii) Previous studies observed Pst isolates with a low virulence spectrum tended to be highly heterozygous [39,60].…”

Section: Discussionmentioning

confidence: 92%

Whole-genome sequencing of Puccinia striiformis f. sp. tritici mutant isolates identifies avirulence gene candidates

Xia

Wang

et al. 2020

BMC Genomics

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Background: The stripe rust pathogen, Puccinia striiformis f. sp. tritici (Pst), threats world wheat production. Resistance to Pst is often overcome by pathogen virulence changes, but the mechanisms of variation are not clearly understood. To determine the role of mutation in Pst virulence changes, in previous studies 30 mutant isolates were developed from a least virulent isolate using ethyl methanesulfonate (EMS) mutagenesis and phenotyped for virulence changes. The progenitor isolate was sequenced, assembled and annotated for establishing a high-quality reference genome. In the present study, the 30 mutant isolates were sequenced and compared to the wide-type isolate to determine the genomic variation and identify candidates for avirulence (Avr) genes. Results: The sequence reads of the 30 mutant isolates were mapped to the wild-type reference genome to identify genomic changes. After selecting EMS preferred mutations, 264,630 and 118,913 single nucleotide polymorphism (SNP) sites and 89,078 and 72,513 Indels (Insertion/deletion) were detected among the 30 mutant isolates compared to the primary scaffolds and haplotigs of the wild-type isolate, respectively. Deleterious variants including SNPs and Indels occurred in 1866 genes. Genome wide association analysis identified 754 genes associated with avirulence phenotypes. A total of 62 genes were found significantly associated to 16 avirulence genes after selection through six criteria for putative effectors and degree of association, including 48 genes encoding secreted proteins (SPs) and 14 non-SP genes but with high levels of association (P ≤ 0.001) to avirulence phenotypes. Eight of the SP genes were identified as avirulence-associated effectors with high-confidence as they met five or six criteria used to determine effectors. Conclusions: Genome sequence comparison of the mutant isolates with the progenitor isolate unraveled a large number of mutation sites along the genome and identified high-confidence effector genes as candidates for avirulence genes in Pst. Since the avirulence gene candidates were identified from associated SNPs and Indels caused by artificial mutagenesis, these avirulence gene candidates are valuable resources for elucidating the mechanisms of the pathogen pathogenicity, and will be studied to determine their functions in the interactions between the wheat host and the Pst pathogen.

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“…Chen, unpublished data). In the United States, the Pst population reproduces asexually (34,132). A segregating population has been developed on barberry from selfing PST-127, a predominant race since 2007.…”

Section: Determination Of Homozygous and Heterozygous Virulencesmentioning

confidence: 99%

Role of Alternate Hosts in Epidemiology and Pathogen Variation of Cereal Rusts

Zhao

Wang

Chen

et al. 2016

Annu. Rev. Phytopathol.

128

104

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Cereal rusts, caused by obligate and biotrophic fungi in the genus Puccinia, are important diseases that threaten world food security. With the recent discovery of alternate hosts for the stripe rust fungus (Puccinia striiformis), all cereal rust fungi are now known to be heteroecious, requiring two distinct plant species serving as primary or alternate hosts to complete their sexual life cycle. The roles of the alternate hosts in disease epidemiology and pathogen variation vary greatly from species to species and from region to region because of different climatic and cropping conditions. We focus this review on rust fungi of small grains, mainly stripe rust, stem rust, leaf rust, and crown rust of wheat, barley, oat, rye, and triticale, with emphases on the contributions of alternate hosts to the development and management of rust diseases.

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Virulence and Molecular Analyses Support Asexual Reproduction of Puccinia striiformis f. sp. tritici in the U.S. Pacific Northwest

Cited by 40 publications

References 55 publications

Genome re‐sequencing and simple sequence repeat markers reveal the existence of divergent lineages in the Canadian Puccinia striiformis f. sp. tritici population with extensive DNA methylation

Genome re‐sequencing and simple sequence repeat markers reveal the existence of divergent lineages in the Canadian Puccinia striiformis f. sp. tritici population with extensive DNA methylation

Whole-genome sequencing of Puccinia striiformis f. sp. tritici mutant isolates identifies avirulence gene candidates

Role of Alternate Hosts in Epidemiology and Pathogen Variation of Cereal Rusts

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