Jens Boch | Search PubMed

PubMed2026

TALEs, TALENs, and TALE Base Editors: From Plant Pathology to Biotechnology.

TALEs (transcription activator-like effectors) are an excellent example of how studying pathogen-host interactions can lead to significant biotechnology inventions. TALEs are bacterial effectors that are translocated into plant cells via a bacterial type III secretion system. Once inside the host cell, they are imported into the nucleus to bind specific promoters and induce expression of target genes, thereby supporting the bacterial infection. TALEs are found throughout many, but not all, Xanthomonas pathovars, which can be severe pathogens of different crops. The key feature of TALEs is their modular DNA-binding domain, which allows a simple evolutionary adaptation to novel DNA sequences as well as simple cloning of designer TALEs with desired DNA-binding specificity. Accordingly, TALE nucleases started the genome-editing revolution, and TALE base editors are the latest tools to efficiently edit chloroplast and mitochondrial genomes. We review recent advances in Xanthomonas genomics, synthesize current knowledge about naturally occurring TALEs, and highlight current roles of TALEs in genome editing and synthetic biology.

Xanthomonas↗

PubMed2024

Designer TALEs enable discovery of cell death-inducer genes.

Transcription activator-like effectors (TALEs) in plant-pathogenic Xanthomonas bacteria activate expression of plant genes and support infection or cause a resistance response. PthA4AT is a TALE with a particularly short DNA-binding domain harboring only 7.5 repeats which triggers cell death in Nicotiana benthamiana; however, the genetic basis for this remains unknown. To identify possible target genes of PthA4AT that mediate cell death in N. benthamiana, we exploited the modularity of TALEs to stepwise enhance their specificity and reduce potential target sites. Substitutions of individual repeats suggested that PthA4AT-dependent cell death is sequence specific. Stepwise addition of repeats to the C-terminal or N-terminal end of the repeat region narrowed the sequence requirements in promoters of target genes. Transcriptome profiling and in silico target prediction allowed the isolation of two cell death inducer genes, which encode a patatin-like protein and a bifunctional monodehydroascorbate reductase/carbonic anhydrase protein. These two proteins are not linked to known TALE-dependent resistance genes. Our results show that the aberrant expression of different endogenous plant genes can cause a cell death reaction, which supports the hypothesis that TALE-dependent executor resistance genes can originate from various plant processes. Our strategy further demonstrates the use of TALEs to scan genomes for genes triggering cell death and other relevant phenotypes.

Cell Death↗