Role of TAL effectors in Xanthomonas-bean interaction and contribution to common bacterial blight management

La pathogénie des bactéries du genre Xanthomonas repose en partie sur leur capacité à injecter des effecteurs TAL (transcription activator-like) dans la cellule végétale. Ces effecteurs agissent comme des facteurs de transcription eucaryotes en induisant des gènes de sensibilité chez la plante hôte afin de favoriser l’infection. L’objectif de cette thèse est de mieux comprendre l’interaction Xanthomonas-haricot, et notamment le rôle des effecteurs TAL dans la graisse commune causée par Xanthomonas phaseoli pv. phaseoli et X. citri pv. fuscans. Pour cela, une étude transcriptomique a été menée pour évaluer l’impact de Xanthomonas sur le transcriptome du haricot en contextes résistant et sensible. Cette étude a permis de révéler des gènes et des voies métaboliques en lien avec la résistance ou la sensibilité de la plante.A l’aide d’une combinaison d’approches transcriptomiques et de tests de pouvoir pathogène, les cibles potentielles de deux effecteurs TAL ont été étudiées. Ces approches ont montré que XfuTAL1 et XfuTAL2 étaient importants pour l’agressivité de Xanthomonas et que XfuTAL1 induisait le gène de sensibilité PvAIL1 codant un facteur de transcription. Cette étude a aussi révélé que la structure atypique de XfuTAL2 augmentait sa capacité d’accroche à l’ADN et jouerait potentiellement un rôle dans la pathogénie. Par ailleurs, une nouvelle méthode de phénotypage a été mise au point pour évaluer l’agressivité de Xanthomonas sur haricot. Ensemble, ces découvertes permettent d’apporter de nouvelles perspectives pour le développement de résistances à Xanthomonas chez le haricot et soulignent l'importance des effecteurs TAL dans ce pathosystème.The pathogenicity of bacteria from the genus Xanthomonas is partly based on their ability to inject TAL effectors (transcription activator-like effectors) inside the plant cell. TAL effectors act as eukaryotic transcription factors by inducing the transcription of susceptibility genes in the host plant to promote infection. The objective of this thesis is to better understand Xanthomonas-bean interaction and more particularly the role of TAL effectors in common bacterial blight of bean caused by Xanthomonas phaseoli pv. phaseoli and X. citri pv. fuscans. To this end, transcriptomic analyses were conducted to evaluate the impact of Xanthomonas on the bean transcriptome in resistant and susceptible contexts. This study revealed genes and metabolic pathways related to resistance or susceptibility of the plant.Using a combination of transcriptomics and pathogenicity tests, the potential targets of two TAL effectors were studied. These approaches showed that XfuTAL1 and XfuTAL2 were important for the aggressiveness of Xanthomonas, and that XfuTAL1 induced the PvAIL1 susceptibility gene encoding a transcription factor. This study also revealed that the atypical structure of XfuTAL2 increased its ability to bind DNA and potentially participated to pathogenicity. In addition, a new phenotyping method was developed to evaluate the aggressiveness of Xanthomonas on bean. Together, these findings provide new insights into the development of Xanthomonas resistance in beans and highlight the importance of TAL effectors in this pathosystem

Rôle des effecteurs TAL dans l'interaction Xanthomonas-haricot et apports dans la lutte contre la graisse commune

The pathogenicity of bacteria from the genus Xanthomonas is partly based on their ability to inject TAL effectors (transcription activator-like effectors) inside the plant cell. TAL effectors act as eukaryotic transcription factors by inducing the transcription of susceptibility genes in the host plant to promote infection. The objective of this thesis is to better understand Xanthomonas-bean interaction and more particularly the role of TAL effectors in common bacterial blight of bean caused by Xanthomonas phaseoli pv. phaseoli and X. citri pv. fuscans. To this end, transcriptomic analyses were conducted to evaluate the impact of Xanthomonas on the bean transcriptome in resistant and susceptible contexts. This study revealed genes and metabolic pathways related to resistance or susceptibility of the plant.Using a combination of transcriptomics and pathogenicity tests, the potential targets of two TAL effectors were studied. These approaches showed that XfuTAL1 and XfuTAL2 were important for the aggressiveness of Xanthomonas, and that XfuTAL1 induced the PvAIL1 susceptibility gene encoding a transcription factor. This study also revealed that the atypical structure of XfuTAL2 increased its ability to bind DNA and potentially participated to pathogenicity. In addition, a new phenotyping method was developed to evaluate the aggressiveness of Xanthomonas on bean. Together, these findings provide new insights into the development of Xanthomonas resistance in beans and highlight the importance of TAL effectors in this pathosystem.La pathogénie des bactéries du genre Xanthomonas repose en partie sur leur capacité à injecter des effecteurs TAL (transcription activator-like) dans la cellule végétale. Ces effecteurs agissent comme des facteurs de transcription eucaryotes en induisant des gènes de sensibilité chez la plante hôte afin de favoriser l’infection. L’objectif de cette thèse est de mieux comprendre l’interaction Xanthomonas-haricot, et notamment le rôle des effecteurs TAL dans la graisse commune causée par Xanthomonas phaseoli pv. phaseoli et X. citri pv. fuscans. Pour cela, une étude transcriptomique a été menée pour évaluer l’impact de Xanthomonas sur le transcriptome du haricot en contextes résistant et sensible. Cette étude a permis de révéler des gènes et des voies métaboliques en lien avec la résistance ou la sensibilité de la plante.A l’aide d’une combinaison d’approches transcriptomiques et de tests de pouvoir pathogène, les cibles potentielles de deux effecteurs TAL ont été étudiées. Ces approches ont montré que XfuTAL1 et XfuTAL2 étaient importants pour l’agressivité de Xanthomonas et que XfuTAL1 induisait le gène de sensibilité PvAIL1 codant un facteur de transcription. Cette étude a aussi révélé que la structure atypique de XfuTAL2 augmentait sa capacité d’accroche à l’ADN et jouerait potentiellement un rôle dans la pathogénie. Par ailleurs, une nouvelle méthode de phénotypage a été mise au point pour évaluer l’agressivité de Xanthomonas sur haricot. Ensemble, ces découvertes permettent d’apporter de nouvelles perspectives pour le développement de résistances à Xanthomonas chez le haricot et soulignent l'importance des effecteurs TAL dans ce pathosystème

Genetic and molecular control of sexual and asexual reproduction in strawberry

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Common bacterial blight of bean: a model of seed transmission and pathological convergence

Xanthomonas citri pv. fuscans (Xcf) and Xanthomonas phaseoli pv. phaseoli (Xpp) are the causal agents of common bacterial blight of bean (CBB), an important disease worldwide that remains difficult to control. These pathogens belong to distinct species within the Xanthomonas genus and have undergone a dynamic evolutionary history including the horizontal transfer of genes encoding factors probably involved in adaptation to and pathogenicity on common bean. Seed transmission is a key point of the CBB disease cycle, favouring both vertical transmission of the pathogen and worldwide distribution of the disease through global seed trade. Taxonomy: Kingdom: Bacteria; phylum: Proteobacteria; class: Gammaproteobacteria; order: Lysobacterales (also known as Xanthomonadales); family: Lysobacteraceae (also known as Xanthomonadaceae); genus: Xanthomonas; species: X. citri pv. fuscans and X. phaseoli pv. phaseoli (Xcf-Xpp). Host range: The main host of Xcf-Xpp is the common bean (Phaseolus vulgaris). Lima bean (Phaseolus lunatus) and members of the Vigna g enus (Vigna aconitifolia, Vigna angularis, Vigna mungo, Vigna radiata, and Vigna umbellata) are also natural hosts of Xcf-Xpp. Natural occurrence of Xcf-Xpp has been reported for a handful of other legumes such as Calopogonium sp., Pueraria sp., pea (Pisum sativum), Lablab purpureus, Macroptilium lathyroides, and Strophostyles helvola. There are conflicting reports concerning the natural occurrence of CBB agents on tepary bean (Phaseolus acutifolius) and cowpea (Vigna unguiculata subsp. unguiculata). Symptoms: CBB symptoms occur on all aerial parts of beans, that is, seedlings, leaves, stems, pods, and seeds. Symptoms initially appear as water-soaked spots evolving into necrosis on leaves, pustules on pods, and cankers on twigs. In severe infections, defoliation and wilting may occur. Distribution: CBB is distributed worldwide, meaning that it is frequently encountered in most places where bean is cultivated in the Americas, Asia, Africa, and Oceania, except for arid tropical areas. Xcf-Xpp are regulated nonquarantine pathogens in Europe and are listed in the A2 list by the European and Mediterranean Plant Protection Organization (EPPO). Genome: The genome consists of a single circular chromosome plus one to four extrachromosomal plasmids of various sizes, for a total mean size of 5.27 Mb with 64.7% GC content and an average predicted number of 4,181 coding sequences. Disease control: Management of CBB is based on integrated approaches that comprise measures aimed at avoiding Xcf-Xpp introduction through infected seeds, cultural practices to limit Xcf-Xpp survival between host crops, whenever possible the use of tolerant or resistant bean genotypes, and chemical treatments, mainly restricted to copper compounds. The use of pathogen-free seeds is essential in an effective management strategy and requires appropriate sampling, detection, and identification methods. Useful websites: https://gd.eppo.int/taxon/ XANTPH, https://gd.eppo.int/taxon/ XANTFF, and http://www.cost.eu/COST_Actio ns/ca/CA16107

How to flower continuously in strawberry and rosa?

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How to flower continuously in strawberry and rosa?

absen

Common bean resistance to Xanthomonas is associated with upregulation of the salicylic acid pathway and downregulation of photosynthesis

International audienceackground Common bacterial blight (CBB) caused byXanthomonas phaseolipv.phaseoliandXanthomonas citripv.fuscansis one of the major threats to common bean crops (Phaseolus vulgarisL.). Resistance to CBB is particularly complex as 26 quantitative resistance loci to CBB have been described so far. To date, transcriptomic studies after CBB infection have been very scarce and the molecular mechanisms underlying susceptibility or resistance are largely unknown. Results We sequenced and annotated the genomes of two common bean genotypes being either resistant (BAT93) or susceptible (JaloEEP558) to CBB. Reciprocal BLASTp analysis led to a list of 20,787 homologs between these genotypes and the common bean reference genome (G19833), which provides a solid dataset for further comparative analyses. RNA-Seq after inoculation withX. phaseolipv.phaseolishowed that the susceptible genotype initiated a more intense and diverse biological response than the resistant genotype. Resistance was linked to upregulation of the salicylic acid pathway and downregulation of photosynthesis and sugar metabolism, while susceptibility was linked to downregulation of resistance genes and upregulation of the ethylene pathway and of genes involved in cell wall modification. Conclusions This study helps better understanding the mechanisms occurring during the early colonization phase of common bean byXanthomonasand unveils new actors potentially important for resistance and susceptibility to CBB. We discuss the potential link between the pathways induced during bean colonization and genes induced by transcription activator-like effectors (TALEs), as illustrated in otherXanthomonaspathovars

How to flower continuously in strawberry and rosa?

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Comparison of pelvic and para-aortic lymphadenectomy versus para-aortic lymphadenectomy alone for locally advanced FIGO stage IB2 to IIB cervical cancer using a propensity score matching analysis: Results from the FRANCOGYN study group

International audienceINTRODUCTION:Pre-treatment evaluation of nodal status is crucial in women presenting with locally advanced cervical cancer (LACC). However, the prognostic impact of surgical staging remains to be proved, as published results comparing surgical versus radiological staging are contradictory. The aim of this study was to compare the prognosis of women with FIGO stage IB2-IIB CC who underwent surgical nodal staging including either exclusive para-aortic lymphadenectomy (PAL) or comprehensive pelvic + para-aortic lymphadenectomy (P-PAL).MATERIALS AND METHODS:Data of 314 women with FIGO stage IB2 to IIB CC treated between January 2000 and January 2015 were retrospectively abstracted from nine French institutions. The prognosis and outcomes were compared by Propensity score (PS) matching (PSM) analysis.RESULTS:The median follow-up was 33 months (2-114). When comparing women who underwent PAL vs P-PAL, the recurrence rates were 26% (37/144) and 28% (41/144), respectively (p = 0.595). The respective 3-year recurrence free survival (RFS) for P-PAL and PAL were 72.9% (95% CI, 65.7-81.0) and 70.7% (95% CI, 62.4-80.2), (p = 0.394). The respective 3-year overall survival (OS) rates for P-PAL and PAL were 86.8% (95% CI, 81.1-92.9) and 78.6% (95% CI, 70.4-87.7) (p = 0.592). In the sub-group of women with lymph node metastases, RFS was improved for women who underwent P-PAL compared to those with exclusive PAL (p = 0.027), with no difference in OS (p = 0.187).CONCLUSIONS:Comprehensive P-PAL does not seem to be of significant therapeutic benefit compared to exclusive PAL

Patterns of recurrence and prognosis in locally advanced FIGO stage IB2 to IIB cervical cancer: Retrospective multicentre study from the FRANCOGYN group

International audienceIntroductionEvidence-based data describing patterns of recurrence and prognosis in women with FIGO stage IB2 to IIB locally advanced cervical cancer (LACC) are scarce. The purpose of this study was to analyse patterns of recurrence in LACC and their correlation with prognosis, depending on FIGO stage, lymph node (LN) status and treatment modalities. The endpoints of this study were the type of recurrence (locoregional or distant, and time to recurrence), the recurrence free survival, the overall survival and the cumulative incidence for both locoregional and distant recurrence.Materials and methodsData of women with FIGO stage IB2 to IIB CC treated between April 1996 and May 2016 were retrospectively abstracted from nine French institutions.ResultsThe median follow-up for the 501 women included was 35.6 months. Recurrences were observed in 158 (31.5%), with a mean time to recurrence of 20.7 months. Women with IIB CC had poorer prognosis, lower 3-year RFS and higher 3-year cumulative incidence of both locoregional and distant recurrences. Women with positive or unknown LN status had poorer prognosis with higher 3-year cumulative incidence of distant recurrence. Women who underwent concomitant chemo-radiotherapy ± vaginal brachytherapy had poorer prognosis, with lower 3-year RFS and higher 3-year cumulative incidence of distant recurrence.ConclusionsRecurrence location and time to recurrence differ widely depending on the FIGO stage, LN status and treatment modalities, with potential impact on follow-up modalities and therapeutic approaches