Two TAL effectors ofXanthomonas citripv.malvacearumtargetGhSWEET15as the susceptibility genes for bacterial blight of cotton

Abstract

AbstractBacterial Blight of Cotton (BBC) caused byXanthomonas citripv.malvacearum(Xcm) is an important and destructive disease affecting cotton plants. Transcription activator-like effectors (TALEs) released by the pathogen regulate cotton resistance to the susceptibility. In this study, we sequenced the whole genome ofXcmXss-V2-18 and identified eighttalgenes; seven on the plasmids and one on the chromosome. Deletion and complementation experiments of Xss-V2-18talgenes demonstrated that Tal1b is required for full virulence on cotton. Transcriptome profiling coupled with TALE-binding element prediction revealed that Tal1b targetsGhSWEET15A04/D04andGhSWEET15D02simultaneously. Expression analysis confirmed the independent inducibility ofGhSWEET15A04/D04andGhSWEET15D02by Tal1b, whereasGhSWEET15A04/D04is additionally targeted by Tal1. Moreover, GUS (β-glucuronidase) andXa10-mediated HR (hypersensitive response) assays indicated that the EBEs are required for the direct and specific activation of the candidate targets by Tal1 and Ta1b. These findings may advance our understanding of the dynamics between TALEs and EBEs, and decipher a simple and effective DNA-binding mechanism that could lead to the development of more efficient methods for gene editing and transgenic research.