title: Transcriptomes ofRalstonia solanacearumduring Root Colonization ofSolanum commersonii.
abstract: Bacterial wilt of potatoes-also called brown rot-is a devastating disease caused by the vascular pathogenRalstonia solanacearumthat leads to significant yield loss. As in other plant-pathogen interactions, the first contacts established between the bacterium and the plant largely condition the disease outcome. Here, we studied the transcriptome ofR. solanacearumUY031 early after infection in two accessions of the wild potatoSolanum commersoniishowing contrasting resistance to bacterial wilt. Total RNAs obtained from asymptomatic infected roots were deep sequenced and for 4,609 out of the 4,778 annotated genes in strain UY031 were recovered. Only 2 genes were differentially-expressed between the resistant and the susceptible plant accessions, suggesting that the bacterial component plays a minor role in the establishment of disease. On the contrary, 422 genes were differentially expressed (DE)in plantacompared to growth on a synthetic rich medium. Only 73 of these genes had been previously identified as DE in a transcriptome ofR. solanacearumextracted from infected tomato xylem vessels. Virulence determinants such as the Type Three Secretion System (T3SS) and its effector proteins, motility structures, and reactive oxygen species (ROS) detoxifying enzymes were induced during infection ofS. commersonii. On the contrary, metabolic activities were mostly repressed during early root colonization, with the notable exception of nitrogen metabolism, sulfate reduction and phosphate uptake. Several of theR. solanacearumgenes identified as significantly up-regulated during infection had not been previously described as virulence factors. This is the first report describing theR. solanacearumtranscriptome directly obtained from infected tissue and also the first to analyze bacterial gene expression in the roots, where plant infection takes place. We also demonstrate that the bacterial transcriptomein plantacan be studied when pathogen numbers are low by sequencing transcripts from infected tissue avoiding prokaryotic RNA enrichment.
authors.affiliation: Department of Genetics, University of BarcelonaBarcelona, Spain; Centre for Research in Agricultural Genomics CSIC-IRTA, Autonomous University of BarcelonaBellaterra, Spain.
authors.forename: Marina
authors.initials: M
authors.lastname: Puigvert
authors.affiliation: Department of Biochemistry, University of São Paulo São Paulo, Brazil.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Guarischi-Sousa
authors.affiliation: Department of Genetics, University of BarcelonaBarcelona, Spain; Centre for Research in Agricultural Genomics CSIC-IRTA, Autonomous University of BarcelonaBellaterra, Spain.
authors.forename: Paola
authors.initials: P
authors.lastname: Zuluaga
authors.affiliation: Centre for Research in Agricultural Genomics CSIC-IRTA, Autonomous University of Barcelona Bellaterra, Spain.
authors.forename: Núria S
authors.initials: NS
authors.lastname: Coll
authors.affiliation: Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences (CAS) Shanghai, China.
authors.forename: Alberto P
authors.initials: AP
authors.lastname: Macho
authors.affiliation: Department of Biochemistry, University of São Paulo São Paulo, Brazil.
authors.forename: João C
authors.initials: JC
authors.lastname: Setubal
authors.affiliation: Department of Genetics, University of BarcelonaBarcelona, Spain; Centre for Research in Agricultural Genomics CSIC-IRTA, Autonomous University of BarcelonaBellaterra, Spain.
authors.forename: Marc
authors.initials: M
authors.lastname: Valls
keywords: RNA sequencing; Ralstonia solanacearum; Solanum commersonii; bacterial wilt; disease resistance; potato brown rot; transcriptomics