Nitrogen fertilizer reduces salicylic acid-mediated immunity by activating gibberellin signaling in rice

The environment plays important role in the interaction between plant hosts and pathogens. The application of chemical fertilizer is a crucial breeding technology to enhance crop yield since last century. As the most abundant fertilizer, nitrogen often increases disease susceptibility for crop plants. The underlying mechanism for nitrogen induced disease susceptibility is elusive. Here we found that nitrogen application activate gibberellin signaling by degradation of SLR1, the repressor protein in gibberellin signaling, which result in simultaneously promoting plant growth and disease susceptibility. SLR1, physically interacts with OsNPR1 and consequently facilitate OsNPR1 mediated defense responses. Transcriptome analysis showed that OsNPR1-SLR1 module plays a vital role in transcriptional reprogramming for both disease resistance and plant growth. Increase of SLR1 protein level in gibberellin deficient rice plants neutralizes disease susceptibility but sacrifice yield enhancement under high nitrogen supply. Mutation in SD1, encoding OsGA2ox2, produced more grains than WT，and maintains disease resistance under high nitrogen supply. Taken together, our work reveals the molecular mechanism underlying nitrogen-induced disease susceptibility, and demonstrates that the application of sd1 rice varieties prevent the tradeoff between disease susceptibility and yield increase under high nitrogen supply. Given OsNPR1 physically interacting with SLR1, it is possible OsNPR1-SLR1 protein complex co-regulate transcription.We used WT, OsNPR1-OE, OsNPR1-OE/slr1-1, slr1-1 to conduct RNA-seq to examine common targets of OsNPR1 and SLR1.