PCR amplification of the Irish potato famine pathogen from historic specimens

183

186

The ability of weeds to proliferate into nonindigenous habitats has been attributed to escape from their native natural enemies, allowing reallocation of resources from chemical defense into growth and reproduction. Many invasive weeds, however, eventually encounter their native, coevolved enemies in areas of introduction. Examination of herbarium specimens of an invasive phototoxic European weed, Pastinaca sativa , through 152 years reveals phytochemical shifts coincident in time with the accidental introduction of a major herbivore, the parsnip webworm, Depressaria pastinacella . Plants collected before the introduction of webworms in North America and during the earliest stages of establishment (1850–1889) are lower in toxic furanocoumarins than all plants subsequently collected in North America and lower than European plant samples collected before 1889. Thus, introduction of a major specialist herbivore can increase noxiousness of a species in its area of introduction, illuminating a potential consequence of classical biocontrol programs involving insect herbivores and poisonous weeds.

mentioning

confidence: 99%

Increase in toxicity of an invasive weed after reassociation with its coevolved herbivore

Zangerl

Berenbaum

2005

183

186

“…The US-1 lineage is not found widely in extant Mexican populations of P. infestans (12,23,24), whereas this lineage is still found in other populations around the world including the Andes. We sequenced the mtDNA from historic specimens of P. infestans from the Irish famine and found the Ia haplotype was common (25,26). The US-1 lineage (Ib mtDNA haplotype) did not cause the famine, but was identified in more recent samples from the Andean region in Ecuador and Bolivia (26).…”

mentioning

confidence: 99%

An Andean origin of Phytophthora infestans inferred from mitochondrial and nuclear gene genealogies

Gómez-Alpízar

Carbone

Ristaino

2007

138

113

Phytophthora infestans (Mont.) de Bary caused the 19th century Irish Potato Famine. We assessed the genealogical history of P. infestans using sequences from portions of two nuclear genes (␤-tubulin and Ras) and several mitochondrial loci P3, (rpl14, rpl5, tRNA) and P4 (Cox1) from 94 isolates from South, Central, and North America, as well as Ireland. Summary statistics, migration analyses and the genealogy of current populations of P. infestans for both nuclear and mitochondrial loci are consistent with an ''out of South America'' origin for P. infestans. Mexican populations of P. infestans from the putative center of origin in Toluca Mexico harbored less nucleotide and haplotype diversity than Andean populations. Coalescent-based genealogies of all loci were congruent and demonstrate the existence of two lineages leading to present day haplotypes of P. infestans on potatoes. The oldest lineage associated with isolates from the section Anarrhichomenun including Solanum tetrapetalum from Ecuador was identified as Phytophthora andina and evolved from a common ancestor of P. infestans. Nuclear and mitochondrial haplotypes found in Toluca Mexico were derived from only one of the two lineages, whereas haplotypes from Andean populations in Peru and Ecuador were derived from both lineages. Haplotypes found in populations from the U.S. and Ireland was derived from both ancestral lineages that occur in South America suggesting a common ancestry among these populations. The geographic distribution of mutations on the rooted gene genealogies demonstrate that the oldest mutations in P. infestans originated in South America and are consistent with a South American origin.late blight ͉ oomycetes ͉ phylogeography ͉ Solanum tuberosum ͉ stamenopiles

“…Detection of ancient microbial DNA in historical samples has proved valuable for studying infectious diseases of humans, animals (9), and plants (10,11). An opportunity to investigate the long-term dynamics of P. nodorum and M. graminicola populations is provided by the availability of PCR assays and the existence of an archive of samples from the long-term Broadbalk winter wheat experiment (12).…”

mentioning

confidence: 99%

Wheat archive links long-term fungal pathogen population dynamics to air pollution

Bearchell

Fraaije

Shaw

et al. 2005

164

143

We used the PCR to study the presence of two plant pathogens in archived wheat samples from a long-term experiment started in 1843. The data were used to construct a unique 160-yr time-series of the abundance of Phaeosphaeria nodorum and Mycosphaerella graminicola, two important pathogens of wheat. During the period since 1970, the relative abundance of DNA of these two pathogens in the samples has reflected the relative importance of the two wheat diseases they cause in U.K. disease surveys. Unexpectedly, changes in the ratio of the pathogens over the 160-yr period were very strongly correlated with changes in atmospheric pollution, as measured by SO 2 emissions. This finding suggests that long-term, economically important, changes in pathogen populations can be influenced by anthropogenically induced environmental changes.Mycosphaerella graminicola ͉ quantitative PCR ͉ Phaeosphaeria nodorum ͉ septoria diseases ͉ sulfur