Host adaptation and speciation through hybridization and polyploidy in Phytophthora.

PLoS One 2013 26;8(12):e85385. Epub 2013 Dec 26.

Department of Crop Protection, Ghent University, Ghent, Belgium.

It is becoming increasingly evident that interspecific hybridization is a common event in phytophthora evolution. Yet, the fundamental processes underlying interspecific hybridization and the consequences for its ecological fitness and distribution are not well understood. We studied hybridization events in phytophthora clade 8b. This is a cold-tolerant group of plant pathogenic oomycetes in which six host-specific species have been described that mostly attack winter-grown vegetables. Hybrid characterization was done by sequencing and cloning of two nuclear (ITS and Ypt1) and two mitochondrial loci (Cox1 and Nadh1) combined with DNA content estimation using flow cytometry. Three different mtDNA haplotypes were recovered among the presumed hybrid isolates, dividing the hybrids into three types, with different parental species involved. In the nuclear genes, additivity, i.e. the presence of two alleles coming from different parents, was detected. Hybrid isolates showed large variations in DNA content, which was positively correlated with the additivity in nuclear loci, indicating allopolyploid hybridization followed by a process of diploidization. Moreover, indications of homeologous recombination were found in the hybrids by cloning ITS products. The hybrid isolates have been isolated from a range of hosts that have not been reported previously for clade 8b species, indicating that they have novel pathogenic potential. Next to this, DNA content measurements of the non-hybrid clade 8b species suggest that polyploidy is a common feature of this clade. We hypothesize that interspecific hybridization and polyploidy are two linked phenomena in phytophthora, and that these processes might play an important and ongoing role in the evolution of this genus.

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0085385PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3873470PMC
February 2015

Publication Analysis

Top Keywords

hybrid isolates
12
dna content
12
interspecific hybridization
12
hybridization polyploidy
8
clade species
8
hybridization
6
novel pathogenic
4
nuclear loci
4
content estimation
4
combined dna
4
nadh1 combined
4
estimation flow
4
cytometry three
4
species indicating
4
mtdna haplotypes
4
three mtdna
4
additivity nuclear
4
flow cytometry
4
pathogenic potential
4
indicating novel
4

Altmetric Statistics

Similar Publications