6 research outputs found
Recommended from our members
The Irish potato famine pathogen Phytophthora infestans originated in central Mexico rather than the Andes
Phytophthora infestans is a destructive plant pathogen best known
for causing the disease that triggered the Irish potato famine and
remains the most costly potato pathogen to manage worldwide.
Identification of P. infestanâs elusive center of origin is critical to
understanding the mechanisms of repeated global emergence of
this pathogen. There are two competing theories, placing the origin
in either South America or in central Mexico, both of which are
centers of diversity of Solanum host plants. To test these competing
hypotheses, we conducted detailed phylogeographic and approximate
Bayesian computation analyses, which are suitable approaches
to unraveling complex demographic histories. Our analyses used
microsatellite markers and sequences of four nuclear genes sampled
from populations in the Andes, Mexico, and elsewhere. To infer the
ancestral state, we included the closest known relatives Phytophthora
phaseoli, Phytophthora mirabilis, and Phytophthora ipomoeae,
as well as the interspecific hybrid Phytophthora andina. We
did not find support for an Andean origin of P. infestans; rather, the
sequence data suggest a Mexican origin. Our findings support the
hypothesis that populations found in the Andes are descendants
of the Mexican populations and reconcile previous findings of ancestral
variation in the Andes. Although centers of origin are well
documented as centers of evolution and diversity for numerous crop
plants, the number of plant pathogens with a known geographic
origin are limited. This work has important implications for our understanding
of the coevolution of hosts and pathogens, as well as
the harnessing of plant disease resistance to manage late blight.Keywords: coalescent analysis, biological invasion, oomycete, population genetics, stramenopil
Recommended from our members
Phytophthora Community Structure Analyses in Oregon Nurseries Inform Systems Approaches to Disease Management
Nursery plants are important vectors for plant pathogens. Understanding what pathogens occur in nurseries in different production stages can be useful to the development of integrated systems approaches. Four horticultural nurseries in Oregon were sampled every 2 months for 4 years to determine the identity and community structure of Phytophthora spp. associated with different sources and stages in the nursery production cycle. Plants, potting media, used containers, water, greenhouse soil, and container yard substrates were systematically sampled from propagation to the field. From 674 Phytophthora isolates recovered, 28 different species or taxa were identified. The most commonly isolated species from plants were Phytophthora plurivora (33%), P. cinnamomi (26%), P. syringae (19%), and P. citrophthora (11%). From soil and gravel substrates, P. plurivora accounted for 25% of the isolates, with P. taxon Pgchlamydo, P. cryptogea, and P. cinnamomi accounting for 18, 17, and 15%, respectively. Five species (P. plurivora, P. syringae, P. taxon Pgchlamydo, P. gonapodyides, and P. cryptogea) were found in all nurseries. The greatest diversity of taxa occurred in irrigation water reservoirs (20 taxa), with the majority of isolates belonging to internal transcribed spacer clade 6, typically including aquatic opportunists. Nurseries differed in composition of Phytophthora communities across years, seasons, and source within the nursery. These findings suggest likely contamination hazards and target critical control points for management of Phytophthora disease using a systems approach
Excel file with PCR-RFLP patterns for identification of nursery Phytophthora spp.
<p>Contains restriction fragement length polymorphism data and GenBank Accession numbers for common nursery <em>Phytophthora</em> species found in Oregon.</p
The Irish potato famine pathogen <i>Phytophthora infestans</i> originated in central Mexico rather than the Andes
Phytophthora infestans is a destructive plant pathogen best known for causing the disease that triggered the Irish potato famine and remains the most costly potato pathogen to manage worldwide. Identification of P. infestanâs elusive center of origin is critical to understanding the mechanisms of repeated global emergence of this pathogen. There are two competing theories, placing the origin in either South America or in central Mexico, both of which are centers of diversity of Solanum host plants. To test these competing hypotheses, we conducted detailed phylogeographic and approximate Bayesian computation analyses, which are suitable approaches to unraveling complex demographic histories. Our analyses used microsatellite markers and sequences of four nuclear genes sampled from populations in the Andes, Mexico, and elsewhere. To infer the ancestral state, we included the closest known relatives Phytophthora phaseoli, Phytophthora mirabilis, and Phytophthora ipomoeae, as well as the interspecific hybrid Phytophthora andina. We did not find support for an Andean origin of P. infestans; rather, the sequence data suggest a Mexican origin. Our findings support the hypothesis that populations found in the Andes are descendants of the Mexican populations and reconcile previous findings of ancestral variation in the Andes. Although centers of origin are well documented as centers of evolution and diversity for numerous crop plants, the number of plant pathogens with a known geographic origin are limited. This work has important implications for our understanding of the coevolution of hosts and pathogens, as well as the harnessing of plant disease resistance to manage late blight
Analysis of global populations of Phytophthora cinnamomi suggests presence of two dominant clonal lineages and evidence of sex in Southeast Asia
Phylogeography of the wideâhost range panglobal plant pathogen Phytophthora cinnamomi
Various hypotheses have been proposed regarding the origin of the plant pathogen Phytophthora cinnamomi. P. cinnamomi is a devastating, highly invasive soilborne pathogen associated with epidemics of agricultural, horticultural and forest plantations and native ecosystems worldwide. We conducted a phylogeographic analysis of populations of this pathogen sampled in Asia, Australia, Europe, southern and northern Africa, South America, and North America. Based on genotyping-by-sequencing, we observed the highest genotypic diversity in Taiwan and Vietnam, followed by Australia and South Africa. Mating type ratios were in equal proportions in Asia as expected for a sexual population. Simulations based on the index of association suggest a partially sexual, semi-clonal mode of reproduction for the Taiwanese and Vietnamese populations while populations outside of Asia are clonal. Ancestral area reconstruction provides new evidence supporting Taiwan as the ancestral area, given our sample, indicating that this region might be near or at the centre of origin for this pathogen as speculated previously. The Australian and South African populations appear to be a secondary centre of diversity following migration from Taiwan or Vietnam. Our work also identified two panglobal, clonal lineages PcG1-A2 and PcG2-A2 of A2 mating type found on all continents. Further surveys of natural forests across Southeast Asia are needed to definitively locate the actual centre of origin of this important plant pathogen.Agricultural Research Service, Grant/Award Number: 2072-22000-041-00-D; National Institute of Food and Agriculture, Grant/Award Number: 2011-68004-30154 and 2018-67013-27823info:eu-repo/semantics/publishedVersio