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The Rice <i>ILI2</i> Locus Is a Bidirectional Target of the African <i>Xanthomonas oryzae</i> pv. <i>oryzae</i> Major Transcription Activator-like Effector TalC but Does Not Contribute to Disease Susceptibility
oleh: Hinda Doucouré, Florence Auguy, Servane Blanvillain-Baufumé, Sandrine Fabre, Marc Gabriel, Emilie Thomas, Fleur Dambreville, Coline Sciallano, Boris Szurek, Ousmane Koita, Valérie Verdier, Sébastien Cunnac
| Format: | Article |
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| Diterbitkan: | MDPI AG 2022-05-01 |
Deskripsi
<i>Xanthomonas oryzae</i> pv. <i>oryzae</i> (<i>Xoo</i>) strains that cause bacterial leaf blight (BLB) limit rice (<i>Oryza sativa</i>) production and require breeding more resistant varieties. Transcription activator-like effectors (TALEs) activate transcription to promote leaf colonization by binding to specific plant host DNA sequences termed effector binding elements (EBEs). <i>Xoo</i> major TALEs universally target susceptibility genes of the SWEET transporter family. TALE-unresponsive alleles of clade III <i>OsSWEET</i> susceptibility gene promoter created with genome editing confer broad resistance on Asian <i>Xoo</i> strains. African <i>Xoo</i> strains rely primarily on the major TALE TalC, which targets <i>OsSWEET14</i>. Although the virulence of a <i>talC</i> mutant strain is severely impaired, abrogating <i>OsSWEET14</i> induction with genome editing does not confer equivalent resistance on African <i>Xoo</i>. To address this contradiction, we postulated the existence of a TalC target susceptibility gene redundant with <i>OsSWEET14</i>. Bioinformatics analysis identified a rice locus named ATAC composed of the <i>INCREASED LEAF INCLINATION 2</i> (<i>ILI2</i>) gene and a putative lncRNA that are shown to be bidirectionally upregulated in a TalC-dependent fashion. Gain-of-function approaches with designer TALEs inducing ATAC sequences did not complement the virulence of a <i>Xoo</i> strain defective for <i>SWEET</i> gene activation. While editing the TalC EBE at the ATAC loci compromised TalC-mediated induction, multiplex edited lines with mutations at the <i>OsSWEET14</i> and ATAC loci remained essentially susceptible to African <i>Xoo</i> strains. Overall, this work indicates that ATAC is a probable TalC off-target locus but nonetheless documents the first example of divergent transcription activation by a native TALE during infection.