Journal Article

Jasmonate promotes auxin-induced adventitious rooting in dark-grown Arabidopsis thaliana seedlings and stem thin cell layers by a cross-talk with ethylene signalling and a modulation of xylogenesis

Gutierrez, Laurent, Hause, Bettina, Veloccia, Angela, Piacentini, Diego, Falasca, Giuseppina, Altamura, Maria Maddalena, Fattorini, Laura, Della Rovere, Federica

2018

Overview

Background Adventitious roots (ARs) are often necessary for plant survival, and essential for successful micropropagation. In Arabidopsis thaliana dark-grown seedlings AR-formation occurs from the hypocotyl and is enhanced by application of indole-3-butyric acid (IBA) combined with kinetin (Kin). The same IBA + Kin-treatment induces AR-formation in thin cell layers (TCLs). Auxin is the main inducer of AR-formation and xylogenesis in numerous species and experimental systems. Xylogenesis is competitive to AR-formation in Arabidopsis hypocotyls and TCLs. Jasmonates (JAs) negatively affect AR-formation in de-etiolated Arabidopsis seedlings, but positively affect both AR-formation and xylogenesis in tobacco dark-grown IBA + Kin TCLs. In Arabidopsis the interplay between JAs and auxin in AR-formation vs xylogenesis needs investigation. In de-etiolated Arabidopsis seedlings, the Auxin Response Factors ARF6 and ARF8 positively regulate AR-formation and ARF17 negatively affects the process, but their role in xylogenesis is unknown. The cross-talk between auxin and ethylene (ET) is also important for AR-formation and xylogenesis, occurring through EIN3/EIL1 signalling pathway. EIN3/EIL1 is the direct link for JA and ET-signalling. The research investigated JA role on AR-formation and xylogenesis in Arabidopsis dark-grown seedlings and TCLs, and the relationship with ET and auxin. The JA-donor methyl-jasmonate (MeJA), and/or the ET precursor 1-aminocyclopropane-1-carboxylic acid were applied, and the response of mutants in JA-synthesis and -signalling, and ET-signalling investigated. Endogenous levels of auxin, JA and JA-related compounds, and ARF6 , ARF8 and ARF17 expression were monitored. Results MeJA, at 0.01 μM, enhances AR-formation, when combined with IBA + Kin, and the response of the early-JA-biosynthesis mutant dde2–2 and the JA-signalling mutant coi1–16 confirmed this result . JA levels early change during TCL-culture, and JA/JA-Ile is immunolocalized in AR-tips and xylogenic cells. The high AR-response of the late JA-biosynthesis mutant opr3 suggests a positive action also of 12-oxophytodienoic acid on AR-formation . The crosstalk between JA and ET-signalling by EIN3/EIL1 is critical for AR-formation, and involves a competitive modulation of xylogenesis. Xylogenesis is enhanced by a MeJA concentration repressing AR-formation, and is positively related to ARF17 expression. Conclusions The JA concentration-dependent role on AR-formation and xylogenesis, and the interaction with ET opens the way to applications in the micropropagation of recalcitrant species.

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: 1-aminocyclopropane-1-carboxylic acid / Acids / Adventitious rooting / adventitious roots / Agriculture / Arabidopsis / Arabidopsis thaliana / ARF17 / Auxins / Biomedical and Life Sciences / Biosynthesis / Butyric acid / Carboxylic acids / Cell culture / Cellular signal transduction / Composition / Crosstalk / Development and cell biology / EIN3/EIL1 / Ethylene / Gene expression / Hypocotyls / indole butyric acid / Indole-3-butyric acid / Investigations / Jasmonate / Jasmonates / jasmonic acid / Kinetin / Life Sciences / methyl jasmonate / Micropropagation / Modulation / Mutants / Physiological aspects / Plant biochemistry / Plant Sciences / recalcitrant species / Research Article / Rooting / Roots (Botany) / Seedlings / Signal transduction / Signaling / Thin cell layers / Thin films / Tips / Tobacco / Tree Biology