Natural hybrids of resident and introduced Phytophthora species proliferating on multiple new hosts

• Published in: European journal of plant pathology Vol. 117; no. 1; pp. 25 - 33
• Main Authors: Man in 't Veld, Willem A, Cock, Arthur W. A. M. de, Summerbell, Richard C
• Format: Journal Article
• Language: English
• Published: Dordrecht Dordrecht : Kluwer Academic Publishers 2007; Springer; Springer Nature B.V
• Subjects: Biological and medical sciences; Cloning; Enzymes; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; Hybrids; Introduced species; Phytopathology. Animal pests. Plant and forest protection; Phytophthora; Netherlands; Europe; Plant pathology; P. cactorum; Microbiology; Plant pathogen; Enzyme; Isozyme; Phycomycetes; Cytochrome-c oxidase; evolution; hybridization; Strain; Fungi; Allele; Plant; Gene; P. hedraiandra; Host range; New species; Oxidoreductases; Phytophthora; Thallophyta
• ISSN: 0929-1873; 1573-8469
• DOI: 10.1007/s10658-006-9065-9

Several atypical Phytophthora strains, isolated from a range of horticultural hosts, were tentatively identified as P. cactorum. Numerous abortive oospores were observed in these strains and isozyme analysis showed all were heterozygous for the dimeric malic enzyme (MDHP). More detailed comparisons indicated that their MDHP alleles matched those of both P. cactorum and P. hedraiandra. Cloning and sequencing of the nuclear ribosomal internal transcribed spacer (ITS) regions of the atypical P. cactorum strains demonstrated the presence of sequences characteristic for both P. cactorum and P. hedraiandra. It was concluded that the atypical strains represented hybrids between the resident P. cactorum and the apparently recently introduced P. hedraiandra. Most strains had the mitochondrially inherited cytochrome oxidase I (Cox I) gene typical of one putative parent P. hedraiandra, while one single strain had that of the other putative parent, consistent with the hybrid hypothesis. Our data also suggest that the hybrids are evolving. The hybrids have proliferated on multiple new hosts in the Netherlands.