Arabidopsis MYC2 Interacts with DELLA Proteins in Regulating Sesquiterpene Synthase Gene Expression

Abstract

Arabidopsis thaliana flowers emit volatile terpenes, which may function in plant-insect interactions. Here, we report that Arabidopsis MYC2, a basic helix-loop-helix transcription factor, directly binds to promoters of the sesquiterpene synthase genes TPS21 and TPS11 and activates their expression. Expression of TPS21 and TPS11 can be induced by the phytohormones gibberellin (GA) and jasmonate (JA), and both inductions require MYC2. The induction of TPS21 and TPS11 results in increased emission of sesquiterpene, especially (E)-b-caryophyllene. DELLAs, the GA signaling repressors, negatively affect sesquiterpene biosynthesis, as the sesquiterpene synthase genes were repressed in plants overaccumulating REPRESSOR OF GA1-3 (RGA), one of the Arabidopsis DELLAs, and upregulated in a penta DELLA-deficient mutant. Yeast two-hybrid and coimmunoprecipitation assays demonstrated that DELLAs, represented by RGA, directly interact with MYC2. In yeast cells, the N terminus of MYC2 was responsible for binding to RGA. MYC2 has been proposed as a major mediator of JA signaling and crosstalk with abscisic acid, ethylene, and light signaling pathways. Our results demonstrate that MYC2 is also connected to GA signaling in regulating a subset of genes. In Arabidopsis inflorescences, it integrates both GA and JA signals into transcriptional regulation of sesquiterpene synthase genes and promotes sesquiterpene production.

Jasmonate Controls Leaf Growth by Repressing Cell Proliferation and the Onset of Endoreduplication while Maintaining a Potential Stand-By Mode

“…This other class of plantspecific hormones plays crucial roles in the mechanisms promoting plant growth and development, notably by triggering the degradation of plant growth repressors, the DELLA proteins (for review, see Harberd et al, 2009). Reinforcing the role of DELLAs as integrators of plant hormone and environmental change responses, recent studies have shown the interaction of DELLAs with JAZ proteins (Hou et al, 2010;Wild et al, 2012;Yang et al, 2012) as well as the MYC2 transcription factor (Hong et al, 2012;Wild et al, 2012). In addition, DELLAs negatively affect plant organ growth by reducing both cell proliferation and cell expansion (Achard et al, 2009).…”

“…Therefore, more than an exit from proliferation, we observe inhibition and entry in stand-by mode; as a result, both the rate of division and entry into endoreduplication are negatively affected. Interestingly, several analyses report cross talk between JAs and GAs (Navarro et al, 2008;Cheng et al, 2009;Hong et al, 2012;Yang et al, 2012). This other class of plantspecific hormones plays crucial roles in the mechanisms promoting plant growth and development, notably by triggering the degradation of plant growth repressors, the DELLA proteins (for review, see Harberd et al, 2009).…”

Light-specific transcriptional regulation of the accumulation of carotenoids and phenolic compounds in rice leaves

“…1). 9,10 The accumulation of carotenoids is also closely linked to the intracellular levels of GA and ABA. Biosynthesis of carotenoids and GA share a common biosynthetic precursor, i.e.…”

Volatile terpenoids: multiple functions, biosynthesis, modulation and manipulation by genetic engineering

“…Similarly, the MYB4 transcriptional factor was a repressor of one of the enzymes in the cinnamate-4-hydroxylase, phenylpropanoid pathway and controlled the flux in petunia flowers (Colquhoun et al 2011). Similarly, MYC2 activated two sesquiterpene synthase genes (TPS11, TPS21) through the jasmonic acid (JA) and gibberellic acid signaling pathway in A. thaliana during inflorescence (Hong et al 2012). In roses, the up-regulation of terpenoid pathways occurred via the overexpression of the PRODUCTION OF ANTHOCYANIN PIGMENT1 (PAP1) transcriptional factor (Zvi et al 2012).…”