Sexual recombination and genetic diversity in Iranian populations of Pyrenophora teres

The mountain pine beetle (MPB; Dendroctonus ponderosae Hopkins, 1902) forms beneficial symbiotic associations with fungi. Here we explored the fine-scale spatial genetic structure of three of those fungi using single nucleotide polymorphism. We found that single mated pairs of beetles carry not only multiple fungal species, but also multiple genotypes of each species into their galleries. We observed genetic diversity at a fine spatial scale. Most of the diversity was found within and among galleries with nonsignificant diversity among trees. We observed clonal propagation almost exclusively within galleries. Ophiostoma montium (Rumbold) Arx possessed a larger expected number of multilocus genotypes and lower linkage disequilibrium than Grosmannia clavigera (Rob.-Jeffr. & R.W. Davidson) Zipfel, Z.W. de Beer & M.J. Wingf. and Leptographium longiclavatum S.W. Lee, J.J. Kim & C. Breuil. More than 80% of fungal samples were genetically unrelated, a result that parallels what has been observed in the beetles. The proportion of genetically related samples within galleries was higher in O. montium (40%) than in G. clavigera (20%) or L. longiclavatum (6%), likely the consequence of within-gallery sexual recombination in O. montium. The underlying genetic diversity reported here and the differences among fungal species could enable the symbiont community to quickly respond to new environmental conditions or changes in the host, enhancing the maintenance of this multipartite relationship and allowing the MPB to colonize new habitats.

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Evidence for Sexual Recombination in Didymella tanaceti Populations, and Their Evolution Over Spring Production in Australian Pyrethrum Fields

Phytopathology ◽

10.1094/phyto-08-17-0280-r ◽

2019 ◽

Vol 109 (1) ◽

pp. 155-168 ◽

Cited By ~ 3

Author(s):

Tamieka L. Pearce ◽

Jason B. Scott ◽

Stacey J. Pilkington ◽

Sarah J. Pethybridge ◽

Frank S. Hay

Keyword(s):

Genetic Diversity ◽

Mating Type ◽

Sampling Period ◽

Genotypic Diversity ◽

Tan Spot ◽

Late Winter ◽

Linkage Equilibrium ◽

Mating Types ◽

Isolation Frequency ◽

Sexual Recombination

Tan spot, caused by Didymella tanaceti, is one of the most important foliar diseases affecting pyrethrum in Tasmania, Australia. Population dynamics, including mating-type ratios and genetic diversity of D. tanaceti, was characterized within four geographically separated fields in both late winter and spring 2012. A set of 10 microsatellite markers was developed and used to genotype 774 D. tanaceti isolates. Isolates were genotypically diverse, with 123 multilocus genotypes (MLG) identified across the four fields. Fifty-eight MLG contained single isolates and Psex analysis estimated that, within many of the recurrent MLG, there were multiple clonal lineages derived from recombination. Isolates of both mating types were at a 1:1 ratio following clone correction in each field at each sampling period, which was suggestive of sexual recombination. No evidence of genetic divergence of isolates of each mating type was identified, indicating admixture within the population. Linkage equilibrium in two of the four field populations sampled in late winter could not be discounted following clone correction. Evaluation of temporal changes in gene and genotypic diversity identified that they were both similar for the two sampling periods despite an increased D. tanaceti isolation frequency in spring. Genetic differentiation was similar in populations sampled between the two sampling periods within fields or between fields. These results indicated that sexual reproduction may have contributed to tan spot epidemics within Australian pyrethrum fields and has contributed to a genetically diverse D. tanaceti population.

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Genomic Regions Associated with Virulence in Pyrenophora teres f. teres Identified by Genome-Wide Association Analysis and Biparental Mapping

Phytopathology ◽

10.1094/phyto-10-19-0372-r ◽

2020 ◽

Vol 110 (4) ◽

pp. 881-891 ◽

Cited By ~ 5

Author(s):

Anke Martin ◽

Paula Moolhuijzen ◽

Yongfu Tao ◽

Judy McIlroy ◽

Simon R. Ellwood ◽

...

Keyword(s):

Association Mapping ◽

Population Level ◽

Genome Wide Association ◽

Pyrenophora Teres ◽

Barley Cultivars ◽

Genome Wide ◽

A Genome ◽

Sexual Recombination ◽

Parastagonospora Nodorum ◽

Genomic Regions

Net form net blotch (NFNB), caused by the fungal pathogen Pyrenophora teres f. teres, is an important foliar disease present in all barley-producing regions of the world. This fungus is a hemibiotrophic and heterothallic ascomycete, where sexual recombination can lead to changes in disease expression in the host. Knowledge of the genetic architecture and genes involved in virulence is vital to increase the durability of NFNB resistance in barley cultivars. We used a genome-wide association mapping approach to characterize P. teres f. teres genomic regions associated with virulence in Australian barley cultivars. One hundred eighty-eight P. teres f. teres isolates collected across five Australian states were genotyped using Diversity Arrays Technology sequence markers and phenotyped across 20 different barley genotypes. Association mapping identified 14 different genomic regions associated with virulence, with the majority located on P. teres f. teres chromosomes 3 and 5 and one each present on chromosomes 1, 6, and 9. Four of the regions identified were confirmed by quantitative trait loci (QTL) mapping. The QTL regions are discussed in the context of their genomic architecture together with examination of their gene contents, which identified 20 predicted effectors. The number of QTL shown in this study at the population level clearly illustrates a complex genetic basis of P. teres f. teres virulence compared with pure necrotrophs, such as the wheat pathogens Parastagonospora nodorum and Parastagonospora tritici-repentis.

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The Mediterranean fruit fly (Ceratitis capitata) in Iran: genetic diversity and comparison with other countries

Journal of Entomological and Acarological Research ◽

10.4081/jear.2015.4055 ◽

2015 ◽

Vol 47 (1) ◽

pp. 20 ◽

Cited By ~ 1

Author(s):

M. Rajabiyan ◽

M. Shayanmehr ◽

M. Mohammadi Sharif

Keyword(s):

Genetic Diversity ◽

Fruit Fly ◽

Mediterranean Fruit Fly ◽

Mazandaran Province ◽

Northern Iran ◽

Important Pest ◽

Different Populations ◽

Low Levels ◽

The Mediterranean ◽

Iranian Populations

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann) is an economically important pest on fruits all over the world. The origin of this fly is thought to be from Africa, but it has recently expanded its distribution in many geographic regions including Iran. Due to the wide spread of this pest in Iran and its serious damage to fruit on trees, including citrus orchards of northern Iran, the present study was conducted firstly to investigate genetic diversity within populations of C. capitata based on the sequences of three mitochondrial DNA (mtDNA) genes including cytochrome C oxidase I (COI), NAHD dehydrogenase subunits 4 and 5 (ND4 and ND5) and secondly to compare the Iranian haplotypes with those found in other countries. Results of this study indicated low levels of genetic diversity (four, four and three haplotypes among different populations of this pest, respectively for the COI, ND4 and ND5 genes) in northern Iranian populations. The genetic similarity and very low levels of genetic diversity of northern Iranian populations suggest that the pest colonisation occurred relatively recently. In addition, haplotypes of Mazandaran province are similar to haplotypes of those countries that have recently been infected by this pest.

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