Somatic hybridization in the Uredinales.

  title={Somatic hybridization in the Uredinales.},
  author={Robert F. Park and Colin R. Wellings},
  journal={Annual review of phytopathology},
Rust fungi are cosmopolitan in distribution and parasitize a wide range of plants, including economically important crop species such as wheat. Detailed regional, national, and continental surveys of pathogenic variability in wheat-attacking rust pathogens over periods of up to 90 years have shown that in the absence of sexual recombination, genetic diversity is generated by periodic introduction of exotic isolates, single-step mutation, and somatic hybridization. Laboratory studies have… 

Nonhost resistance to rust pathogens – a continuation of continua

It is highlighted how the quantitative nature of disease resistance in these intermediate interactions is caused by a continuum of defense barriers, which a pathogen needs to overcome for successfully establishing itself in the host.

Emergence of the Ug99 lineage of the wheat stem rust pathogen through somatic hybridisation

It is shown that Ug99 arose by somatic hybridisation and nuclear exchange between dikaryons, and shares one haploid nucleus genotype with a much older African lineage of Pgt, with no recombination or reassortment.

Extensive somatic nuclear exchanges shape global populations of the wheat leaf rust pathogen Puccinia triticina

Haplotype-specific phylogenetic analysis of Puccinia triticina reveals that repeated somatic exchange events have shuffled haploid nuclei between long-term clonal lineages, leading to a global population representing different combinations of a limited number of haploid genomes.

Whole-genome sequencing of multiple isolates of Puccinia triticina reveals asexual lineages evolving by recurrent mutations

The results suggest that recurrent mutation and selection play a major role in differentiation within the clonal lineages of P. triticina.

Population genomics of Puccinia graminis f.sp. tritici highlights the role of admixture in the origin of virulent wheat rust races

This study uses long-read sequencing to develop a haplotype-resolved genome assembly of a U.S. isolate of Pgt and shows that SVs and admixture events appear to play an important role in broadening Pgt virulence and the origin of highly virulent races.

Pathogenomic Analysis of Wheat Yellow Rust Lineages Detects Seasonal Variation and Host Specificity

This analysis revealed that P. striiformis lineages recently detected in Europe are extremely diverse and in fact similar to globally dispersed populations, and identified a considerable shift in the UK P.striiformis population structure including the first identification of one infamous race known as Kranich.

Multinuclei Occurred Under Cryopreservation and Enhanced the Pathogenicity of Melampsora larici-populina

The multinuclear isolate is different from the wild-type isolate in terms of phenotype and genotype; this multinucleation phenomenon in urediniospores improves the pathogenesis and environmental fitness of M. larici-populina.

Inheritance and Linkage of Virulence Genes in Chinese Predominant Race CYR32 of the Wheat Stripe Rust Pathogen Puccinia striiformis f. sp. tritici

Comparisons with previous studies indicated complex interactions between virulence genes in the pathogen and resistance genes in wheat lines and the results are useful for understanding the plant-pathogen interactions and developing wheat cultivars with effective and durable resistance.

Genetic Relationships of Puccinia striiformis f. sp. tritici in Southwestern and Northwestern China

Understanding the epidemiology and population genetics of plant pathogens is crucial to formulate efficient predictions of disease outbreaks and achieve sustainable integrated disease management,

Genetic Variability among Presumed Clonal Pathotypes of Puccinia graminis f. sp. tritici in Australia

This research examined the genetic variability among 157 Australian Puccinia graminis f.



Isozyme analysis indicates that a virulent cereal rust pathogen is a somatic hybrid

Somatic hybridization between formae speciales or different strains of the same forma specialis of cereal rusts has often been implicated in the origin of new virulence combinations1–3. It has been

Obligate biotrophy features unraveled by the genomic analysis of rust fungi

The dramatic up-regulation of transcripts coding for small secreted proteins, secreted hydrolytic enzymes, and transporters in planta suggests that they play a role in host infection and nutrient acquisition.

Interspecific hybridization in plant‐associated fungi and oomycetes: a review

This work has shown the potential for interspecific hybridization among pathogens, which results in adaptation to new niches such as new host species, and increased or decreased virulence.

Genotypic variation within a phenotype as a possible basis for somatic hybridization in rust fungi

It is generally considered that the production of new strains of rust by somatic hybridization cannot be adequately explained by hyphal anastomosis and nuclear exchange. Such a mechanism would

Obligate Biotrophy Features Unraveled by the Genomic Analysis of the Rust Fungi, Melampsora larici-populina and Puccinia graminis f. sp. tritici

The dramatic upregulation of transcripts coding for SSPs, secreted hydrolytic enzymes, and transporters in planta suggests that they play a role in host infection and nutrient acquisition.

Production of New Physiologic Races in Puccinia striiformis (Yellow Rust) by Heterokaryosis

Mutation and cytoplasmic change are possible causes of the production of new races, but it seemed to us that heterokaryosis or parasexual phenomena in the uredospore stage (both known in P. graminis) could be involved.

Population structure and diversity in sexual and asexual populations of the pathogenic fungus Melampsora lini

The population genetic structure of wild populations of the plant pathogen Melampsora lini on its host Linum marginale is investigated using amplified fragment length polymorphism (AFLP) markers, two genes underlying pathogen virulence, and phenotypic variation in virulence.


The present study indicates that hybridization between wheat stem rust and rye stem rust can be important in producing new combinations of virulence genes which can attack known genes for resistance in wheat.

Puccinia striiformis in Australia: a review of the incursion, evolution, and adaptation of stripe rust in the period 1979–2006

Data is suggested that BGYR is a new forma specialis of P. striiformis, likely to have little impact on commercial barley, although this may change with further pathotype evolution or the release of susceptible cultivars.