GSE137212
Salicylic Acid Suppresses Apical Hook Formation via NPR1-Mediated Repression of EIN3/EIL1 in Arabidopsis
Salicylic acid (SA) and ethylene (ET) are two important plant hormones that regulate numerous plant growth, development, and stress response processes. Previous studies have suggested functional interplay of SA and ET in defense response, but precisely how these two hormones co-regulate plant growth and development processes remains unclear. The present findings reveal an antagonism between SA and ET in apical hook formation, a process that ensures successful soil emergence of dicotyledonous etiolated seedlings. Exogenous SA inhibited the ET-induced expression of HOOKLESS1 (HLS1) in a manner dependent on ETHYLENE INSENSITIVE3 (EIN3)/EIN3-LIKE1 (EIL1), the core transcription factors in the ET signaling pathway. We found that SA-activated NONEXPRESSER OF PR GENES1 (NPR1) physically interacted with EIN3 and interfered with the direct binding of EIN3 to target gene promoters, including the HLS1 promoter. Transcriptomic analysis further revealed that NPR1 and EIN3/EIL1 coordinately regulated subsets of genes that mediate plant growth and stress responses, suggesting that the interaction between NPR1 and EIN3/EIL1 might be an important mechanism for integrating the SA and ET signaling pathways in multiple physiological processes. Taken together, our findings shed light on the molecular mechanism underlying SA regulation of apical hook formation as well as the antagonism between SA and ET in early seedling establishment and possibly other physiological processes. Overall design: The 3.5-day-old etiolated seedlings of Col-0, ein3-1 eil1-1, and npr1-1 were treated with MS liquid supplemented with or without 500 µM SA for 4 hrs before tissue collection. Three biological replicates were prepared for detection and whole seedlings was used for RNA extraction. Total RNA was extracted using the RNeasy Plant Mini Kit (Qiagen). Magnetic beads with Oligo (dT) are used to isolate mRNA. Agilent 2100 Bioanaylzer and ABI StepOnePlus Real-Time PCR System are used in quantification and qualification of the sample library. mRNA-seq was performed by the Beijing Genomics Institute (BGI) using the Illumina HiSeq X Ten system.