Time-course RNA-seq analysis of the barley MLA1 immune receptor-mediated response to barley powdery mildew fungus Bgh in Arabidopsis thaliana. Arabidopsis thaliana

We report that an intracellular NLR immune receptor from monocotyledonous barley is fully functional in dicotyledonous Arabidopsis thaliana. In contrast to common belief in plant NLR biology, this implies ~150 million years of evolutionary conservation of the underlying immune mechanism. This also suggests a conserved translocation mechanism for pathogen effectors in flowering plants. The deduced connectivity of the NLR to bifurcated signaling pathways likely confers increased robustness against pathogen interception, which could have contributed to the evolutionary preservation of the immune mechanism. RNA-seq experiments in Arabidopsis detected sustained expression of a single major MLA1-dependent gene cluster. Overall design: 3 biological replicates per condition. The Arabidopsis plants without (pps) or with (B12) the MLA1-HA construct in a pen2 pad4 sag101 background were challenged with either the Bgh isolate K1 expressing the cognate AVRA1 effector for MLA1 or the Bgh isolate A6 expressing other AVRA effectors. Samples were collected at 6, 12, 18, 24 hours post inoculation (hpi) of Bgh.