Arabidopsis DELLA and JAZ Proteins Bind the WD-Repeat/bHLH/MYB Complex to Modulate Gibberellin and Jasmonate Signaling Synergy  

Abstract

Integration of diverse environmental and endogenous signals to coordinately regulate growth, development, and defense is essential for plants to survive in their natural habitat. The hormonal signals gibberellin (GA) and jasmonate (JA) antagonistically and synergistically regulate diverse aspects of plant growth, development, and defense. GA and JA synergistically induce initiation of trichomes, which assist seed dispersal and act as barriers to protect plants against insect attack, pathogen infection, excessive water loss, and UV irradiation. However, the molecular mechanism underlying such synergism between GA and JA signaling remains unclear. In this study, we revealed a mechanism for GA and JA signaling synergy and identified a signaling complex of the GA pathway in regulation of trichome initiation. Molecular, biochemical, and genetic evidence showed that the WD-repeat/bHLH/MYB complex acts as a direct target of DELLAs in the GA pathway and that both DELLAs and JAZs interacted with the WD-repeat/bHLH/MYB complex to mediate synergism between GA and JA signaling in regulating trichome development. GA and JA induce degradation of DELLAs and JASMONATE ZIM-domain proteins to coordinately activate the WD-repeat/bHLH/MYB complex and synergistically and mutually dependently induce trichome initiation. This study provides deep insights into the molecular mechanisms for integration of different hormonal signals to synergistically regulate plant development.

The DELLA-CONSTANS Transcription Factor Cascade Integrates Gibberellic Acid and Photoperiod Signaling to Regulate Flowering

“…For example, GLABRA1, PHYTOCHROME INTERACTING FACTORs, MYC2, GLABRA3, ENHANCER OF GLABRA3, Class I TCP, BRASSINAZOLE-RESISTANT1, ETHYLENE INSENSITIVE3, AUXIN RESPONSE FACTOR6, and SPLs, were reported as targets of DELLA proteins to regulate diverse aspects of GA-mediated processes (Yu et al, 2012;Davière et al, 2008Davière et al, , 2014Davière et al, , 2016de Lucas et al, 2008;Feng et al, 2008;Hong et al, 2012;Wild et al, 2012;Qi et al, 2014;Bai et al, 2012;An et al, 2012;Oh et al, 2014). Furthermore, our study and Xu et al (2016) found that the B-box protein CO also interacts with DELLA (Fig.…”

Plant Glandular Trichomes: Natural Cell Factories of High Biotechnological Interest

“…The JA receptor JASMONIC ACID IN-SENSITIVE1, the tomato ortholog of the ubiquitin ligase CORONATINE INSENSITIVE1 in Arabidopsis, is involved in this JA-mediated signaling cascade (Li et al, 2004;Katsir et al, 2008;Kang et al, 2010;Bosch et al, 2014). It remains to be investigated whether a synergistic effect between GA and JA signaling, similar to that observed in Arabidopsis (Qi et al, 2014), also promotes glandular trichome development. The development of multicellular glandular trichomes proceeds through the enlargement of single epidermal cells, followed by several cell divisions to generate a structure perpendicular to the epidermal surface (Fig.…”

Regulation of Jasmonate-Mediated Stamen Development and Seed Production by a bHLH-MYB Complex in Arabidopsis

“…Within this complex, the bHLH factor (such as GL3) interacts with the MYB factors (MYB75 or GL1) via their N-terminal domains, while JAZ repressors competitively interact with the N-terminal domains of these bHLH and MYB factors to disrupt and repress the WD-repeat/bHLH/MYB complex essential for JA-regulated anthocyanin biosynthesis and trichome initiation (Qi et al, , 2014. JA induces the degradation of JAZs to release this WD-repeat/bHLH/MYB complex, which further activates the expression of the downstream genes to enhance anthocyanin biosynthesis and trigger trichome initiation .…”