State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an 271018, China.
State Key Laboratory of Hybrid Rice, Hubei Hongshan Laboratory, College of Life Sciences, Wuhan University, Wuhan 430072, China.
Int J Mol Sci. 2021 Dec 20;22(24):13628. doi: 10.3390/ijms222413628.
delivers transcription activator-like effectors (TALEs) into plant cells to facilitate infection. Following economic principles, the redundant TALEs are rarely identified in Xanthomonas. Previously, we identified the Tal2b, which activates the expression of the rice 2-oxoglutarate-dependent dioxygenase gene to promote infection in the highly virulent strain of pv. HGA4. Here, we reveal that another clustered TALE, Tal2c, also functioned as a virulence factor to target rice , a homologue of . Transferring Tal2c into RS105 induced expression of to coincide with increased susceptibility in rice. Overexpressing caused higher susceptibility and less salicylic acid (SA) production compared to wild-type plants. Moreover, CRISPR-Cas9 system-mediated editing of the effector-binding element in the promoters of or was found to specifically enhance resistance to Tal2b- or Tal2c-transferring strains, but had no effect on resistance to either RS105 or HGA4. Furthermore, transcriptome analysis revealed that several reported SA-related and defense-related genes commonly altered expression in overexpression line compared with those identified in overexpression line. Overall, our results reveal a functional redundancy mechanism of pathogenic virulence in Xoc in which tandem Tal2b and Tal2c specifically target homologues of host genes to interfere with rice immunity by reducing SA.
将转录激活子样效应物（TALEs）递送到植物细胞中以促进感染。根据经济原则，冗余的 TALEs 在黄单胞菌中很少被鉴定出来。先前，我们鉴定了 Tal2b，它激活了水稻 2-氧戊二酸依赖性双加氧酶基因的表达，以促进高度毒力菌株 pv 的感染。HGA4。在这里，我们揭示了另一个簇状 TALE，Tal2c，也作为毒力因子起作用，靶向水稻，这是 的同源物。将 Tal2c 转入 RS105 中会诱导 的表达，与水稻的易感性增加相一致。与野生型植物相比，过表达 导致更高的易感性和更少的水杨酸（SA）产生。此外，CRISPR-Cas9 系统介导的靶基因启动子中效应物结合元件的编辑被发现特异性增强了对 Tal2b 或 Tal2c 转移菌株的抗性，但对 RS105 或 HGA4 的抗性没有影响。此外，转录组分析显示，与鉴定的 过表达系相比，几个报道的 SA 相关和防御相关基因在 过表达系中共同改变了表达。总体而言，我们的结果揭示了 Xoc 中致病毒力的功能冗余机制，其中串联的 Tal2b 和 Tal2c 特异性靶向宿主基因的同源物，通过减少 SA 来干扰水稻的免疫。
