title: Loop-mediated isothermal amplification for detection of the tomato and potato late blight pathogen, Phytophthora infestans.
abstract: OBJECTIVE
  To design and validate a colorimetric loop-mediated isothermal amplification assay for rapid detection of Phytophthora infestans DNA.
  
  
  RESULTS
  Two sets of loop-mediated isothermal amplification (LAMP) primers were designed and evaluated for their sensitivity and specificity for P. infestans. ITSII primers targeted a portion of the internal transcribed spacer region of ribosomal DNA. These primers had a limit of detection of 2 pg P. infestans DNA and cross-reacted with the closely related species Phytophthora nicotianae. Rgn86_2 primers, designed to improve assay specificity, targeted a portion of a conserved hypothetical protein. These primers had a limit of detection of 200 pg P. infestans DNA and did not cross-react with P. nicotianae. The specificity of the Rgn86_2 assay was tested further using the closely related species P. andina, P. ipomoeae, P. mirabilis and P. phaseoli. Cross-reactions occurred with P. andina and P. mirabilis, but neither species occurs on tomato or potato. Both primer sets were able to detect P. infestans DNA extracted from tomato late blight leaf lesions.
  
  
  CONCLUSIONS
  Two colorimetric LAMP assays detected P. infestans DNA from pure cultures as well as infected leaf tissue. The ITSII primers had higher sensitivity, and the Rgn86_2 primers had higher specificity.
  
  
  CONCLUSIONS
  This is the first report of a LAMP assay for the detection of P. infestans, the causal organism of potato and tomato late blight. These assays have potential for immediate utility in plant disease research and diagnostic laboratories.
authors.affiliation: Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Geneva, NY, USA.
authors.forename: Z R
authors.initials: ZR
authors.lastname: Hansen
authors.affiliation: Horticultural Crops Research Laboratory, USDA Agricultural Research Service, Corvallis, OR, USA.
authors.forename: B J
authors.initials: BJ
authors.lastname: Knaus
authors.affiliation: Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA.
authors.forename: J F
authors.initials: JF
authors.lastname: Tabima
authors.affiliation: Horticultural Crops Research Laboratory, USDA Agricultural Research Service, Corvallis, OR, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Press
authors.affiliation: Department of Plant Pathology and Microbiology, University of California, Riverside, CA, USA.
authors.forename: H S
authors.initials: HS
authors.lastname: Judelson
authors.affiliation: Horticultural Crops Research Laboratory, USDA Agricultural Research Service, Corvallis, OR, USA.|Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA.
authors.forename: N J
authors.initials: NJ
authors.lastname: Grünwald
authors.affiliation: Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Geneva, NY, USA.
authors.forename: C D
authors.initials: CD
authors.lastname: Smart
mesh_terms: D017931:DNA Primers; D018551:Solanum lycopersicum / Q000382:microbiology; D021141:Nucleic Acid Amplification Techniques / Q000379:methods*; D055750:Phytophthora infestans / Q000235:genetics* / Q000302:isolation & purification; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000382:microbiology; D011198:Solanum tuberosum / Q000382:microbiology
chemical_list: D017931:DNA Primers
keywords: Phytophthora infestans; agriculture; diagnostics; late blight; loop-mediated isothermal amplification; plant pathology; potato; tomato