Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Cell Host and Microbe 638-649+ 5 2019 fdi:010077209 ENG Cell Host and Microbe 1931-3128 ISI:000496264400012 5 10.1016/j.chom.2019.09.014 https://www.documentation.ird.fr/hor/fdi:010077209 https://www.documentation.ird.fr/intranet/publi/2019/11/010077209.pdf 26 Horizon (IRD) Pathogenic bacteria inject effector proteins into host cells to manipulate cellular processes and facilitate the infection. Transcription-activator-like effectors (TALEs), an effector class in plant pathogenic bacteria, transcriptionally activate host genes to promote disease. We identify arginine decarboxylase (ADC) genes as the host targets of Brg11, a TALE-like effector from the plant pathogen Ralstonia solanacearum. Brg11 targets a 17-bp sequence that was found to be part of a conserved 50-bp motif, termed the ADC-box, upstream of ADC genes involved in polyamine biosynthesis. The transcribed ADC-box attenuates translation from native ADC mRNAs; however, Brg11 induces truncated ADC mRNAs lacking the ADC-box, thus bypassing this translational control. As a result, Brg11 induces elevated polyamine levels that trigger a defense reaction and likely inhibits bacterial niche competitors but not R. solanacearum. Our findings suggest that Brg11 may give R. solanacearum a competitive advantage and uncover a role for bacterial effectors in regulating ternary microbe-host-microbe interactions. 076 ; 020 UR186