title: A spectroscopy approach to the study of virus infection in the endophytic fungus Epichloë festucae.
abstract: BACKGROUND
  In this work we propose a rapid method based on visible and near-infrared (Vis-NIR) spectroscopy to determine the occurrence of double-stranded RNA (dsRNA) viruses in Epichloë festucae strains isolated from Festuca rubra plants. In addition, we examined the incidence of infections by E. festucae in populations of F. rubra collected in natural grasslands of Western Spain.
  
  
  METHODS
  Vis-NIR spectra (400-2498 nm) from 124 virus-infected and virus-free E. festucae isolates were recorded directly from ground and freeze-dried mycelium. To estimate how well the spectra for uninfected and infected fungal samples could be differentiated, we used partial least-squares discriminant analysis (PLS1-DA) and several data pre-treatments to develop calibration models.
  
  
  RESULTS
  Applying the best regression model, obtained with two sampling years and using standard normal variate (SNV) combined with first derivative transformation to a new validating data set (42 samples), we obtained a correct classification for 75% of the uninfected isolates and up to 86% of the infected isolates.
  
  
  CONCLUSIONS
  The results obtained suggest that Vis-NIR spectroscopy is a promising technology for detection of viral infections in fungal samples when an alternative faster approach is desirable. It provides a tool adequately exact and more time- and cost-saving than the conventional reference analysis.
authors.affiliation: Instituto de Recursos Naturales y Agrobiología de Salamanca, IRNASA-CSIC, Apdo 257, 37071 Salamanca, Spain. cristi2911@hotmail.com
authors.forename: Cristina
authors.initials: C
authors.lastname: Petisco
authors.forename: Balbino
authors.initials: B
authors.lastname: Garcia-Criado
authors.forename: Iñigo
authors.initials: I
authors.lastname: Zabalgogeazcoa
authors.forename: Beatriz R
authors.initials: BR
authors.lastname: Vázquez-de-Aldana
authors.forename: Antonia
authors.initials: A
authors.lastname: Garcia-Ciudad
mesh_terms: D055329:Epichloe / Q000737:chemistry* / Q000302:isolation & purification / Q000821:virology*; D031751:Festuca / Q000382:microbiology; D025282:Mycelium / Q000821:virology; D009172:Mycology / Q000379:methods*; D012328:RNA Viruses / Q000737:chemistry* / Q000254:growth & development*; D013030:Spain; D013057:Spectrum Analysis / Q000379:methods*; D014773:Virology / Q000379:methods*