Electrophoretic karyotyping and mapping of pathotype-specific DNA sequences in Japanese isolates of Verticillium dahliae
ABSTRACT The chromosome number and electrophoretic karyotype of Japanese isolates of Verticillium dahliae were investigated. In a genomic Southern blot analysis of seven isolates probed with a telomere consensus sequence (TTAGGG)5, 12 or 14 bands were observed. Furthermore, pulsed-field gel electrophoresis (PFGE) of these isolates revealed five or six
chromosomal bands. A band (approx. 3.5Mbp) common to all isolates apparently contained more than two chromosomes. From these
results, we concluded that each isolate’s chromosome number is six (an eggplant pathotype isolate) or seven (all isolates
of tomato and sweet pepper pathotypes). Although the chromosome sizes differed among isolates, karyotypes were similar within
tomato and sweet pepper pathotypes. A small chromosome (approx. 1.8Mbp) was observed only in the sweet pepper pathotype.
Subsequent PFGE-Southern hybridization analyses revealed that the three DNA fragments specific to tomato pathotype are located
on the same chromosome. These results suggest that the tomato-pathotype-specific DNA sequences might coexist on one chromosome.
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ABSTRACT: Mating type genes of Verticillium dahliae, a wilt pathogen affecting many plant species, were identified to examine sexual recombination between Japanese pathotypes. We amplified a DNA sequence encoding high mobility group (HMG) box from V. dahliae using PCR. A cloned genomic DNA fragment included a sequence homologous to MAT1-2-1 gene. Despite that sequence's presence in all V. dahliae isolates we used, MAT1-1-1 (an opposite mating type gene) was never amplified. We concluded that V. dahliae is potentially heterothallic. Furthermore, sexual bias practically obviates sexual recombination between Japanese pathotypes. This report describes, for the first time, a mating type gene of phytopathogenic Verticillium.Physiological and Molecular Plant Pathology.
Article: The ascomycete Verticillium longisporum is a hybrid and a plant pathogen with an expanded host range.[show abstract] [hide abstract]
ABSTRACT: Hybridization plays a central role in plant evolution, but its overall importance in fungi is unknown. New plant pathogens are thought to arise by hybridization between formerly separated fungal species. Evolution of hybrid plant pathogens from non-pathogenic ancestors in the fungal-like protist Phytophthora has been demonstrated, but in fungi, the most important group of plant pathogens, there are few well-characterized examples of hybrids. We focused our attention on the hybrid and plant pathogen Verticillium longisporum, the causal agent of the Verticillium wilt disease in crucifer crops. In order to address questions related to the evolutionary origin of V. longisporum, we used phylogenetic analyses of seven nuclear loci and a dataset of 203 isolates of V. longisporum, V. dahliae and related species. We confirmed that V. longisporum was diploid, and originated three different times, involving four different lineages and three different parental species. All hybrids shared a common parent, species A1, that hybridized respectively with species D1, V. dahliae lineage D2 and V. dahliae lineage D3, to give rise to three different lineages of V. longisporum. Species A1 and species D1 constituted as yet unknown taxa. Verticillium longisporum likely originated recently, as each V. longisporum lineage was genetically homogenous, and comprised species A1 alleles that were identical across lineages.PLoS ONE 01/2011; 6(3):e18260. · 4.09 Impact Factor