635 / 2019-04-28 10:45:04

Salicylic Acid Suppresses Apical Hook Formation via NPR1-Mediated Repression of EIN3/EIL1 in Arabidopsis

Hook formation，Salicylic acid，NPR1，EIN3/EIL1

Plant Hormones > Plant Hormones

Salicylic acid (SA) and ethylene (ET) are two important plant hormones that regulate numerous plant growth, development, and stress response processes. However, precisely how these two hormones co-regulate plant growth and development processes remains largely unclear. Our 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 co-regulated subsets of genes that mediate plant growth and stress responses. 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.