title: Transgenerational gene silencing causes gain of virulence in a plant pathogen.
abstract: Avirulence (Avr) genes of plant pathogens encode effector proteins that trigger immunity in plants carrying appropriate resistance (R) genes. The Phytophthora sojae Avr3a gene displays allelic variation in messenger RNA transcript levels. P. sojae strains with detectable Avr3a gene transcripts are avirulent on plants carrying the R-gene Rps3a, whereas strains lacking Avr3a mRNA escape detection by Rps3a and are virulent. Here we show non-Mendelian interactions between naturally occurring Avr3a alleles that result in transgenerational gene silencing, and we identify small RNA molecules of 25 nucleotides that are abundant in gene-silenced strains but not in strains with Avr3a mRNA. This example of transgenerational gene silencing is exceptional because it is naturally occurring and results in gain of virulence in a pathogenic organism.
authors: Agriculture and Agri-Food Canada, 1391 Sandford Street, London, Ontario N5V 4T3, Canada.
authors: Dinah
authors: D
authors: Qutob
authors: B Patrick
authors: BP
authors: Chapman
authors: Mark
authors: M
authors: Gijzen
mesh_terms: D000483:Alleles; D020090:Chromosome Segregation / Q000235:genetics; D003433:Crosses, Genetic; D020868:Gene Silencing; D059014:High-Throughput Nucleotide Sequencing; D010641:Phenotype; D010838:Phytophthora / Q000235:genetics* / Q000472:pathogenicity*; D010935:Plant Diseases / Q000382:microbiology; D012313:RNA / Q000235:genetics; D013025:Glycine max / Q000382:microbiology*; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors / Q000378:metabolism
chemical_list: D037521:Virulence Factors; D012313:RNA