ETHYLENE RESPONSE FACTOR 115 integrates jasmonate and cytokinin signaling machineries to repress adventitious rooting in Arabidopsis

Abstract

Summary Adventitious root initiation (ARI) is a de novo organogenesis program and a key adaptive trait in plants. Several hormones regulate ARI but the underlying genetic architecture that integrates the hormonal crosstalk governing this process remains largely elusive. In this study, we use genetics, genome editing, transcriptomics, hormone profiling and cell biological approaches to demonstrate a crucial role played by the APETALA2/ETHYLENE RESPONSE FACTOR 115 transcription factor. We demonstrate that ERF115 functions as a repressor of ARI by activating the cytokinin (CK) signaling machinery. We also demonstrate that ERF115 is transcriptionally activated by jasmonate (JA), an oxylipin‐derived phytohormone, which represses ARI in NINJA‐dependent and independent manners. Our data indicate that NINJA‐dependent JA signaling in pericycle cells blocks early events of ARI. Altogether, our results reveal a previously unreported molecular network involving cooperative crosstalk between JA and CK machineries that represses ARI.

Red Light Controls Adventitious Root Regeneration by Modulating Hormone Homeostasis in Picea abies Seedlings

“…When JA and CK were combined, no additive or synergistic effect was observed ( Figure 3G), suggesting that they act in the same pathway. These results are in agreement with our previous data that showed that CK signaling is induced by JA to repress AR formation in intact Arabidopsis hypocotyls (Lakehal et al, 2020a).…”

“…When applied exogenously, both JA and 6-Benzylaminopurine (6-BAP) inhibited AR development in a dosedependent manner (Figures 3C, D) and they both repressed the positive effect of exogenous IBA ( Figures 3E, F). These results suggest that JA and CK act downstream of auxin signaling to repress ARI, as has been described for intact Arabidopsis hypocotyls (Gutierrez et al, 2012;Lakehal et al, 2020a). When JA and CK were combined, no additive or synergistic effect was observed ( Figure 3G), suggesting that they act in the same pathway.…”

“…We have previously shown that JA and its bioactive form Jasmonoyol-Isoleucine (JA-Ile) inhibit ARI in Arabidopsis hypocotyls (Gutierrez et al, 2012;Lakehal et al, 2020a). Here, as expected in the case of wounding, JA and JA-Ile were induced…”

“…We have previously shown that ARI in intact etiolated Arabidopsis hypocotyls is under the control of IAA and JA signaling pathways (Gutierrez et al, 2012). More recently we showed that JA and CK cooperatively repress this process (Lakehal et al, 2020a). We therefore hypothesized that light might also modulate phytohormone signaling and/or homeostasis pathways to control ARI in Norway spruce hypocotyls.…”

“…It has been shown that there is interplay among these phytohormones in complex networks and loops that ensure proper AR development (Lakehal and Bellini, 2019). For example, in Arabidopsis thaliana, it has been shown that auxin signaling controls AR formation by modulating JA homeostasis in the hypocotyl (Gutierrez et al, 2012;Lakehal et al, 2019a) and that JA cooperates with CKs to repress AR formation (Lakehal et al, 2020a). Moreover, JA induces the expression of DIOXYGENASE FOR AUXIN OXIDATION 1 (DAO1) in a CORNATINE INSENSTIVE1(COI1)-dependent way.…”