The rice OsERF101 transcription factor regulates the NLR Xa1-mediated perception of TAL effectors and Xa1-mediated immunity

O_LIPlant nucleotide-binding leucine-rich repeat receptors (NLRs) initiate immune responses and the hypersensitive response by recognizing pathogen effectors. Xa1 encodes an NLR with an N-terminal BED domain, and recognizes transcription activator-like (TAL) effectors of Xanthomonas oryzae pv. oryzae (Xoo). The molecular mechanisms controlling the recognition of TAL effectors by Xa1 and the subsequent induction of immunity remain poorly understood. C_LIO_LIXa1 interacts in the nucleus with two TAL effectors via the BED domain. We identified the AP2/ERF-type transcription factor OsERF101/OsRAP2.6 as an interactor with Xa1, and found that it also interacts with the TAL effectors. Overexpression of OsERF101 exhibited an enhanced resistance to an incompatible Xoo strain only in the presence of Xa1, indicating that OsERF101 functions as a positive regulator of Xa1-mediated immunity. Unexpectedly, oserf101 mutants also showed enhanced Xa1-dependent resistance, but in a different manner from the overexpressing plants. This result revealed an additional Xa1-mediated immune pathway that is negatively regulated by OsERF101. Furthermore, OsERF101 directly interacted with the TAL effectors. C_LIO_LIOur results show that OsERF101 regulates the recognition of TAL effectors and the Xa1-mediated activation of the immune response. These data provide new insights into the molecular mechanism of NLR-mediated immunity in plants. C_LI