Designer transcription activator-like effectors enable discovery of cell death-inducer genes

authored by
Roxana A Roeschlin, Sepideh M Azad, René P Grove, Ana Chuan, Lucila García, Regina Niñoles, Facundo Uviedo, Liara Villalobos-Piña, Maria E Massimino, María R Marano, Jens Boch, José Gadea

TALEs (transcription activator-like effectors) 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 harbouring 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.

Institute of Plant Genetics
External Organisation(s)
Instituto Nacional de Tecnología Agropecuaria (INTA)
Instituto de Biología Molecular y celular de Plantas (IBMCP)
Instituto de Biología Molecular y Celular de Rosario (IBR)-Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET)
Plant Physiology
Publication date
Publication status
E-pub ahead of print
Peer reviewed
Electronic version(s) (Access: Open)