title: Changing Ploidy as a Strategy: The Irish Potato Famine Pathogen Shifts Ploidy in Relation to Its Sexuality.
abstract: The oomycete Phytophthora infestans was the causal agent of the Irish Great Famine and is a recurring threat to global food security. The pathogen can reproduce both sexually and asexually, with high potential to adapt to various environments and great risk to break disease resistance genes in potato. As are other oomycetes, P. infestans is regarded to be diploid during the vegetative phase of its life cycle, although some studies reported trisomy and polyploidy. Using microsatellite fingerprinting, genome-wide assessment of single nucleotide polymorphisms, nuclear DNA quantification, and microscopic counting of chromosome numbers, we assessed the ploidy level of a comprehensive selection of isolates. All progenies from sexual populations of P. infestans in nature were found to be diploid, in contrast nearly all dominant asexual lineages, including the most important pandemic clonal lineages US-1 and 13_A2 were triploid. Such triploids possess significantly more allelic variation than diploids. We observed that triploid genotype can change to a diploid genome constitution when exposed to artificial stress conditions. This study reveals that fluctuations in the ploidy level may be a key factor in the adaptation process of this notorious plant destroyer and imposes an extra challenge to control this disease.
authors.affiliation: 1 Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
authors.affiliation: 1 Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
authors.forename: He
authors.initials: H
authors.lastname: Shen
authors.affiliation: 1 Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China.|2 Agricultural Genome Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518124, China; and.
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhou
authors.affiliation: 1 Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Qian
authors.affiliation: 3 Biointeractions & Plant Health, Wageningen University & Research Center, Plant Research International, Wageningen 6700AA, The Netherlands.
authors.forename: Theo
authors.initials: T
authors.lastname: van der Lee
authors.affiliation: 1 Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China.|2 Agricultural Genome Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518124, China; and.
authors.forename: Sanwen
authors.initials: S
authors.lastname: Huang
mesh_terms: D000483:Alleles; D005434:Flow Cytometry; D016681:Genome, Fungal; D018895:Microsatellite Repeats / Q000235:genetics; D055750:Phytophthora infestans / Q000235:genetics*; D010935:Plant Diseases / Q000382:microbiology*; D011003:Ploidies; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D011123:Polyploidy; D012098:Reproduction; D017422:Sequence Analysis, DNA; D011198:Solanum tuberosum / Q000382:microbiology*; D013312:Stress, Physiological / Q000235:genetics