Phytophthora meadii may be a species hybrid

Sansome, Eva; Brasier, C. M.; Hamm, Philip B.

doi:10.1016/s0953-7562(09)81232-x

Cited by 34 publications

(12 citation statements)

References 16 publications

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“…It is also evident that the standard and variant forms are closely related, though the precise evolutionary basis of their rela- tionship remains unclear. In the past, interspecific hybridization has been suggested as an explanation for polyploidy, phylogenetic complexity, and sterility in Phytophthora (31)(32)(33), and synthetic hybrids have been created in the laboratory (34,35). However, to our knowledge there has been no previous demonstration of a naturally occurring hybrid complex in the genus.…”

Section: Resultsmentioning

confidence: 99%

Origin of a new Phytophthora pathogen through interspecific hybridization

Brasier

Cooke

Duncan

1999

Proc. Natl. Acad. Sci. U.S.A.

318

287

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Plant disease epidemics resulting from introductions of exotic fungal plant pathogens are a well known phenomenon. An associated risk—that accelerated pathogen evolution may be occurring as a consequence of genetic exchange between introduced, or introduced and resident, fungal pathogens—is largely unrecognized. This is, in part, because examples of natural, interspecific hybridization in fungi are very rare. Potential evolutionary developments range from the acquisition of new host specificities to emergence of entirely new pathogen taxa. We present evidence from cytological behavior, additive nucleotide bases in repetitive internal transcribed spacer regions of the rRNA-encoding DNA (rDNA), and amplified fragment length polymorphisms of total DNA that a new, aggressive Phytophthora pathogen of alder trees in Europe comprises a range of heteroploid-interspecific hybrids involving a Phytophthora cambivora -like species and an unknown taxon similar to Phytophthora fragariae . The hybrids’ marked developmental instabilities, unusual morphological variability, and evidence for recombination in their internal transcribed spacer profiles indicates that they are of recent origin and that their evolution is continuing. The likelihood of such evolutionary events may be increasing as world trade in plants intensifies. However, routine diagnostic procedures currently in use are insufficiently sensitive to allow their detection.

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Section: Resultsmentioning

confidence: 99%

Origin of a new Phytophthora pathogen through interspecific hybridization

Brasier

Cooke

Duncan

1999

Proc. Natl. Acad. Sci. U.S.A.

318

287

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“…For nadh1, P. hibernalis clustered with P. nicotianae, and P. katsurae had 100% homology with the isolate from Spathiphyllum. Sansome et al (1991) postulated that P. meadii might be a hybrid species, based on variability and instability in chromosome structure, observed in meiosis. This observation could explain for the inconsistencies in the classification of P. meadii in our phylogenetic analysis.…”

Section: Discussionmentioning

confidence: 99%

Phylogenetic analysis of Phytophthora species based on mitochondrial and nuclear DNA sequences

Kroon¹,

Bakker²,

Bosch³

et al. 2004

Fungal Genetics and Biology

421

339

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“…Previously, genetic exchange via interspecific hybridisation in Phytophthora has been suspected in several instances and been shown to occur in the laboratory 24. 26–33 Another natural Phytophthora hybridisation has been conclusively demonstrated most recently: interspecific hybrids of P nicotianae and P cactorum were obtained from diseased ornamentals such as Primula and Spatiphyllum plants grown in hydroponic systems 25. 34…”

Section: Discussionmentioning

confidence: 99%

Standard and Swedish variant types of the hybrid alder Phytophthora attacking alder in Hungary

Nagy

Bakonyi

Érsek

2003

Pest Management Science

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A new Phytophthora disease of common alder (Alnus glutinosa) similar to that previously reported in several countries in Europe has been observed in Hungary. Based on these earlier studies, the alder Phytophthora was considered likely to be a hybrid between P cambivora and a P fragariae-like species: across Europe a range of new alder Phytophthora is spreading that comprise a range of heteroploid hybrids including a 'standard' hybrid type and several other hybrid types termed 'variants'. Phenotypic and molecular features of the pathogen in Hungary were characterised and compared with isolates from elsewhere. The morphologies of five isolates from one region (Hévíz) resembled the common, 'standard' type, whereas the three isolates from another region (Hanság) exhibited traits similar to those of one of the 'variant' types, ie the Swedish 'variant'. Molecular markers of these two groups of Hungarian isolates also represented a good fit to those of the standard type and the Swedish variant, respectively. Isozyme patterns and profiles of restriction fragments of the entire internal transcribed spacer (ITS) region or mitochondrial DNAs and of RAPD-PCR products did not differ within a group, but distinct polymorphisms were exhibited between the two groups of isolates. Southern analysis of random amplified polymorphic DNA (RAPD) revealed the homologous nature of co-migrating bands of P cambivora and the isolates of alder Phytophthora. Furthermore, restriction fragment profiles of the ITS region of ribosomal DNAs and the mtDNAs were consistent with reported biparental origin of alder Phytophthora. The hybrid status of these continuously evolving pathogens raises many issues and challenges concerning efficient control measures.

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Phytophthora meadii may be a species hybrid

Cited by 34 publications

References 16 publications

Origin of a new Phytophthora pathogen through interspecific hybridization

Origin of a new Phytophthora pathogen through interspecific hybridization

Phylogenetic analysis of Phytophthora species based on mitochondrial and nuclear DNA sequences

Standard and Swedish variant types of the hybrid alder Phytophthora attacking alder in Hungary

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