The conjugation of SUMO to the transcription factor MYC2 functions in blue light-mediated seedling development in Arabidopsis

Abstract

A key function of photoreceptor signalling is the coordinated regulation of a large number of genes to optimize plant growth and development. The bHLH transcription factor MYC2 is crucial for regulating gene expression in Arabidopsis thaliana during development in blue light. Here we demonstrate that blue light induces the SUMOylation of MYC2. Non SUMOylatable MYC2 is less effective in suppressing blue light-mediated photomorphogenesis than wild-type MYC2. MYC2 interacts physically with the SUMO proteases SUMO PROTEASE RELATED TO FERTILITY1 (SPF1) and SPF2. Blue light exposure promotes the degradation of SPF1 and SPF2 and enhances the SUMOylation of MYC2. Phenotypic analysis revealed that SPF1/SPF2 function redundantly as positive regulators of blue light-mediated photomorphogenesis. Our data demonstrate that SUMO conjugation does not affect the dimerization of MYC transcription factors but modulates the interaction of MYC2 with its cognate DNA cis-element and with the ubiquitin ligase Plant U-box 10 (PUB10). Finally, we show that non-SUMOylatable MYC2 is less stable and interacts more strongly with PUB10 than the wild type. Taken together, we conclude that SUMO functions as a counterpoint to the ubiquitin-mediated degradation of MYC2, thereby enhancing its function in blue light signalling.

Effects of light spectrum on the morphophysiology and gene expression of lateral branching in Pepino (Solanum muricatum)

“…Only a few studies have reported the model for regulating plant lateral branch development using different light qualities. The photomorphogenesis of plants is induced by light through multiple photoreceptors and abundant related plant morpho-physiological and gene expression processes (Srivastava et al, 2022). The regulatory mechanism of different light qualities on crop morphogenesis is of great significance.…”

Unequal genetic redundancies among MYC bHLH transcription factors underlie seedling photomorphogenesis in Arabidopsis

“…Among MYCs, MYC2 is a dominant player regulating plant defense responses, while MYC3 and MYC4 have a redundant role (Niu et al ., 2011, Ortigosa et al ., 2020). Specifically, the role of MYC2 in light-mediated seedling development has been well established (Yadav et al ., 2005, Gangappa et al ., 2010, Gangappa et al ., 2013b, Sethi et al ., 2014, Chakraborty et al ., 2019, Ortigosa et al ., 2020, Srivastava et al ., 2022). However, the role of MYC3 and MYC4 and their interaction with MYC2 in the seedling photomorphogenesis was unknown.…”

“…Among MYCs, the role of MYC2 in Arabidopsis seedling development is very well established. MYC2 is a key regulator of seedling photomorphogenesis and light-induced gene expression (Yadav et al, 2005, Gangappa et al, 2010, Sethi et al, 2014, Maurya et al, 2015, Chakraborty et al, 2019, Srivastava et al, 2022, Ojha et al, 2023). While the role of MYC2 in light-mediated seedling development has been studied to some extent, that of MYC3 and MYC4 remains unknown.…”

MYC2: A Master Switch for Plant Physiological Processes and Specialized Metabolite Synthesis

“…SUMO conjugation does not affect the dimerization of MYC but modulates the interaction of MYC2 with its cognate DNA cis-element and with the ubiquitin ligase plant U-box 10 (PUB10). Moreover, the non-SUMOylatable MYC2 is less stable and interacts more strongly with PUB10; thus, SUMO functions as a counterpoint to the ubiquitin-mediated degradation of MYC2 [ 45 ]. In addition, E3 ubiquitin ligase can also reduce MYC protein level based on Cullin3 and BPM proteins as substrate junctions.…”