A Conserved Basal Transcription Factor Is Required for the Function of Diverse TAL Effectors in Multiple Plant Hosts

Many Xanthomonas bacteria use transcription activator-like effector (TALE) proteins to activate plant disease susceptibility (S) genes, and this activation contributes to disease. We recently reported that rice basal transcription factor IIA gamma subunit, OsTFIIA gamma 5, is hijacked by TALE-carrying Xanthomonas oryzae infecting the plants. However, whether TFIIA gamma s are also involved in TALE-carrying Xanthomonas-caused diseases in other plants is unknown. Here, molecular and genetic approaches were used to investigate the role of TFIIA gamma s in other plants. We found that TFIIA gamma s are also used by TALE-carrying Xanthomonas to cause disease in other plants. The TALEs of Xanthomonas citri pv. citri (Xcc) causing canker in citrus and Xanthomonas campestris pv. vesicatoria (Xcv) causing bacterial spot in pepper and tomato interacted with corresponding host TFIIA gamma s as in rice. Transcriptionally suppressing TFIIA gamma led to resistance to Xcc in citrus and Xcv in pepper and tomato. The 39th residue of OsTFIIA gamma 5 and citrus CsTFIIA gamma is vital for TALE-dependent induction of plant S genes. As mutated OsTFIIA gamma 5(V39E), CsTFIIA gamma(V39E), pepper CaTFIIA gamma(V39E), and tomato SlTFIIA gamma(V39E) also did not interact with TALEs to prevent disease. These results suggest that TALE-carrying bacteria share a common mechanism for infecting plants. Using TFIIA gamma(V39E)-type mutation could be a general strategy for improving resistance to TALE-carrying pathogens in crops.