@article {Ioos2006511, title = {Genetic characterization of the natural hybrid species Phytophthora alni as inferred from nuclear and mitochondrial DNA analyses}, journal = {Fungal Genetics and Biology}, volume = {43}, number = {7}, year = {2006}, pages = {511 - 529}, abstract = {

The different subspecies of Phytophthora alni, P. alni subsp. alni (Paa), P. alni subsp. uniformis (Pau), and P. alni subsp. multiformis (Pam), are recent and widespread pathogens of alder in Europe. They are believed to be a group of emergent heteroploid hybrids between two phylogenetically close Phytophthora species. Nuclear and mitochondrial DNA analyses were performed, using a broad collection of P. alni and two closely related species, P. cambivora and P. fragariae. (Paa) possesses three different alleles for each of the nuclear genes we studied, two of which are present in Pam as well, whereas the third matches the single allele present in Pau. Moreover, Paa displays common mtDNA patterns with both Pam and Pau. A combination of the data suggests that Paa may have been generated on several occasions by hybridization between Pam and Pau, or their respective ancestors. Pau might have P. cambivora as a species ancestor, whereas Pam seems to have either been generated itself by an ancient reticulation or by autopolyploidization.

}, keywords = {Interspecific hybridization}, issn = {1087-1845}, doi = {DOI: 10.1016/j.fgb.2006.02.006}, url = {http://www.sciencedirect.com/science/article/B6WFV-4JS1TK3-1/2/aead0efc6dc22a393ebadec5b3211855}, author = {Renaud Ioos and Axelle Andrieux and Beno{\'O}t Mar{\'A}ais and Pascal Frey} } @article {MEN:MEN1554, title = {Characterization of microsatellite markers in the interspecific hybrid Phytophthora alni ssp. alni, and cross-amplification with related taxa}, journal = {Molecular Ecology Notes}, volume = {7}, number = {1}, year = {2007}, pages = {133{\textendash}137}, publisher = {Blackwell Publishing Ltd}, abstract = {

Phytophthora alni ssp. alni is an interspecific hybrid oomycete causing a large-scale decay of alders throughout Europe. In this study we developed a set of 10 microsatellite markers that shows promise for population studies and for studying hybridization events between the parental species of the hybrid. Moreover, the genotype and the ploidy of the different subspecies of P. alni might be inferred from the quantitative ratio of amplified genome-specific alleles. Nine primer pairs cross amplified with the related species Phytophthora cambivora and Phytophthora fragariae and yielded distinct alleles.

}, keywords = {genotyping, oomycete, polyploidy}, issn = {1471-8286}, doi = {10.1111/j.1471-8286.2006.01554.x}, url = {http://dx.doi.org/10.1111/j.1471-8286.2006.01554.x}, author = {Renaud Ioos and Barr{\'e}s, Beno{\^{\i}t and Axelle Andrieux and Pascal Frey} } @article {springerlink:10.1007/s10658-005-6233-2, title = {SCAR{\textendash}based PCR primers to detect the hybrid pathogen Phytophthora alni and its subspecies causing alder disease in Europe}, journal = {European Journal of Plant Pathology}, volume = {112}, year = {2005}, note = {10.1007/s10658-005-6233-2}, pages = {323-335}, publisher = {Springer Netherlands}, abstract = {

Since the 1990s, a new Phytophthora species hybrid has been jeopardizing the natural population of alders throughout Europe. This new Phytophthora, P. alni, has been suggested as a natural hybrid between two closely related species of Phytophthora. Little is known about the epidemiology of this pathogen, because its direct isolation is not always satisfactory. In this study we developed three pairs of Polymerase Chain Reaction (PCR) primers derived from Sequence Characterized Amplified Regions (SCAR) that allow discrimination among the three subspecies of P. alni: P. alni subsp. alni, P. alni subsp. uniformis and P. alni subsp. multiformis. These molecular tools were successfully used to detect P. alni directly in different substrates such as infested river water and soil, and necrotic alder bark, without the need for any prior baiting or isolation stages. An Internal Amplification Control (IAC) was included to help discriminate against false negative samples due to the potential presence of inhibitory compounds in DNA extracts. These molecular tools should be useful for epidemiological studies on this emerging disease.

}, issn = {0929-1873}, url = {http://dx.doi.org/10.1007/s10658-005-6233-2}, author = {Renaud Ioos and Husson, Claude and Axelle Andrieux and Pascal Frey} } @article {1227, title = {Distribution and expression of elicitin genes in the interspecific hybrid oomycete Phytophthora alni}, journal = {Appl. Environ. Microbiol.}, volume = {73}, year = {2007}, pages = {5587-5597}, abstract = {

Phytophthora alni subsp. alni, P. alni subsp. multiformis, and P. alni subsp. uniformis are responsible for alder disease in Europe. Class I and II elicitin gene patterns of P. alni subsp. alni, P. alni subsp. multiformis, P. alni subsp. uniformis, and the phylogenetically close species P. cambivora and P. fragariae were studied through mRNA sequencing and 3{\textquoteright} untranslated region (3{\textquoteright}UTR)-specific PCRs and sequencing. The occurrence of multiple 3{\textquoteright}UTR sequences in association with identical elicitin-encoding sequences in P. alni subsp. alni indicated duplication/recombination events. The mRNA pattern displayed by P. alni subsp. alni demonstrated that elicitin genes from all the parental genomes are actually expressed in this allopolyploid taxon. The complementary elicitin patterns resolved confirmed the possible involvement of P. alni subsp. multiformis and P. alni subsp. uniformis in the genesis of the hybrid species P. alni subsp. alni. The occurrence of multiple and common elicitin gene sequences throughout P. cambivora, P. fragariae, and P. alni sensu lato, not observed in other Phytophthora species, suggests that duplication of these genes occurred before the radiation of these species.

}, doi = {doi:10.1128/AEM.00721-07}, url = {http://aem.asm.org/content/73/17/5587.abstract}, author = {Renaud Ioos and Panabi{\`e}res, Franck and Industri, Beno{\^{\i}t and Axelle Andrieux and Pascal Frey} }