Transcriptome analysis of Xanthomonas fragariae in strawberry leaves

Abstract

Xanthomonas fragariae is a quarantine bacterial pathogen that causes angular leaf spot on strawberry. The aim of our study was to analyse the mechanism of interaction of this bacterium with its host plant at the transcriptome level. For this purpose, mRNAs of X. fragariae growing in Wilbrink’s medium and from infected strawberry cv. Elsanta plants were isolated and sequenced using the Illumina MiSeq platform. The expression profiles of the bacteria in Wilbrink’s medium and in planta were very diverse. Of the 3939 CDSs recorded, 1995 had significantly different expression in planta (966 and 1029 genes were down- and upregulated, respectively). Among the genes showing increased expression in planta, those with eggNOG/COG (evolutionary genealogy of genes: Non-supervised Orthologous Groups/Cluster of Orthologous Groups) categories associated with bacterial cell motility, signal transduction, transport and metabolism of inorganic ions and carbohydrates and transcription were overrepresented. Among the genes with the most increased expression in planta, genes primarily associated with flagella synthesis and chemotaxis were found. It is also interesting to note that out of the 31 genes localized on a plasmid, 16 were expressed differently in planta, which may indicate their potential role in plant–pathogen interactions. Many genes with differentiated expression that were localized on chromosome and plasmid encode proteins of unknown function.

Prevalence and Specificity of Chemoreceptor Profiles in Plant-Associated Bacteria

“…In particular, we found that CRs with increased expression in planta , and particularly those required for full bacterial virulence, belonged to high-DPS clusters ( Table 2 ). This list includes CRs that are upregulated in Dickeya dadantii 3937 and Pectobacterium carotovorum WPP14, two soft-rot bacterial strains ( 39 ); Dickeya dianthicola RNS04.9, which grows on macerated potato tubers ( 40 ); and Xanthomonas fragariae , which grows on strawberry leaves ( 41 ). Similarly, we found several CRs with very high DPS values (80%) that were shown to be relevant in Xanthomonas citri virulence ( 42 ) or required for fitness of Pseudomonas savastanoi pv.…”

Genes and Loci Controlling the Resistance of Strawberry (F. ananassa Duch.) to Pathogens

“…Xanthomonas fragariae is a gram-negative bacterium that causes angular spotting of strawberry leaves and is listed in Europe as a quarantine pathogen in the EPPO A2 list (Puławska et al, 2020). This is a potentially serious and insidious disease, first reported in the United States.…”

TheXanthomonas fragariaeeffector XopK suppresses stomatal immunity by perturbing abscisic acid accumulation and signaling pathways in strawberry

“…The virulent Xaf strain LMG25863 was predicted to contain twenty-three T3Es and several putative new effectors (Vandroemme et al, 2013). Furthermore, transcriptome analysis of Xaf in strawberries revealed that T3Es can be functional in Xaf during the pathogenesis process (Gétaz et al, 2020; Puławska et al, 2020). Recently, 47 T3Es were mined based on a machine-learning method, and two novel Xaf T3Es, XopBG and XopBF, were translocated and elicited hypersensitive reaction (HR) on pepper leaves, revealed its possible pathogenic role in Xaf Fap21 (Wagner et al, 2023).…”