title: Evaluation of reference genes for real-time RT-PCR expression studies in the plant pathogen Pectobacterium atrosepticum.
abstract: BACKGROUND
  Real-time RT-PCR has become a powerful technique to monitor low-abundance mRNA expression and is a useful tool when examining bacterial gene expression inside infected host tissues. However, correct evaluation of data requires accurate and reliable normalisation against internal standards. Thus, the identification of reference genes whose expression does not change during the course of the experiment is of paramount importance. Here, we present a study where manipulation of cultural growth conditions and in planta experiments have been used to validate the expression stability of reference gene candidates for the plant pathogen Pectobacterium atrosepticum, belonging to the family Enterobacteriaceae.
  
  
  RESULTS
  Of twelve reference gene candidates tested, four proved to be stably expressed both in six different cultural growth conditions and in planta. Two of these genes (recA and ffh), encoding recombinase A and signal recognition particle protein, respectively, proved to be the most stable set of reference genes under the experimental conditions used. In addition, genes proC and gyrA, encoding pyrroline-5-carboxylate reductase and DNA gyrase, respectively, also displayed relatively stable mRNA expression levels.
  
  
  CONCLUSIONS
  Based on these results, we suggest recA and ffh as suitable candidates for accurate normalisation of real-time RT-PCR data for experiments investigating the plant pathogen P. atrosepticum and potentially other related pathogens.
authors: Norwegian Institute for Agricultural and Environmental Research, Plant Health and Plant Protection Division, Høgskoleveien 7, 1432 As, Norway. gunnhild.takle@bioforsk.no
authors: Gunnhild W
authors: GW
authors: Takle
authors: Ian K
authors: IK
authors: Toth
authors: May B
authors: MB
authors: Brurberg
mesh_terms: D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000235:genetics*; D016973:Pectobacterium carotovorum / Q000235:genetics*; D010935:Plant Diseases / Q000382:microbiology*; D012015:Reference Standards; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D012984:Software; D011198:Solanum tuberosum / Q000382:microbiology*