Jasmonic Acid-Ethylene Crosstalk via ETHYLENE INSENSITIVE 2 Reprograms Arabidopsis Root System Architecture Through Nitric Oxide Accumulation

Abstract

Plant growth and development are tightly regulated by phytohormones, including jasmonic acid (JA) and ethylene (ET), two canonical players in plant defense and in the control of root system architecture. Here, we show that JA inhibits primary root growth and promotes lateral root development while inducing nitric oxide (NO) accumulation in the wild-type (WT) primary root, but not in jar1-1, coi1-1, myc2-1, and myc2-2 Arabidopsis mutants defective in JA biosynthesis or response. NO-related mutants nia1/nia2 and Atnoa1 were indistinguishable in root architectural responses to JA when compared to WT seedlings, and the developmental changes were apparently unrelated to reactive oxygen species (ROS) accumulation. Root growth inhibition by the NO donor, sodium nitroprusside (SNP), was reduced in coi1-1 mutants, and NO accumulation induced the expression of the downstream repressors JAZ1 and JAZ10 at the differentiation and/or meristematic root regions. Comparison of growth of WT, ein2-1, jar1-1, and ein2-1/jar1-1 mutants further revealed a critical role of ETHYLENE INSENSITIVE2 (EIN2) in mediating both JA and NO root sensing. Our results suggest that NO mediates JA signaling during the configuration of the Arabidopsis root system architecture and that EIN2 plays a role in this developmental program.