Interplay of the two ancient metabolites auxin and MEcPP regulates adaptive growth

Abstract

The ancient morphoregulatory hormone auxin dynamically realigns dedicated cellular processes that shape plant growth under prevailing environmental conditions. However, the nature of the stress-responsive signal altering auxin homeostasis remains elusive. Here we establish that the evolutionarily conserved plastidial retrograde signaling metabolite methylerythritol cyclodiphosphate (MEcPP) controls adaptive growth by dual transcriptional and post-translational regulatory inputs that modulate auxin levels and distribution patterns in response to stress. We demonstrate that in vivo accumulation or exogenous application of MEcPP alters the expression of two auxin reporters, DR5:GFP and DII-VENUS, and reduces the abundance of the auxin-efflux carrier PIN-FORMED1 (PIN1) at the plasma membrane. However, pharmacological intervention with clathrin-mediated endocytosis blocks the PIN1 reduction. This study provides insight into the interplay between these two indispensable signaling metabolites by establishing the mode of MEcPP action in altering auxin homeostasis, and as such, positioning plastidial function as the primary driver of adaptive growth.

Retrograde induction of phyB orchestrates ethylene-auxin hierarchy to regulate growth

“…4 C ). We validated this finding by testing Rc grown WT and ceh1 lines expressing the auxin signaling reporter DR5 -GFP (Jiang et al, 2018). The reduced GFP signal in ceh1 was on par with lower IAA levels in the mutant compared to the WT seedling (Fig.…”

“…2 D - F ). This inhibitor interferes with and highly reduces the flux through the pathway and abolishes MEcPP-mediated actions such as formation of otherwise stress-induced subcellular structures known as ER bodies or enhancing the reduced auxin levels in ceh1 mutant plants (Gonzalez-Cabanelas et al, 2015; Wang et al, 2017b; Jiang et al, 2018). We examined hypocotyl growth of red-light grown 7-day-old seedlings that were treated with FSM for 3 days.…”

“…We have previously established that MEcPP-mediated modulation of levels and distribution patterns of auxin (IAA) is via dual transcriptional and post-translational regulatory inputs (Jiang et al, 2018). We specifically demonstrated reduced transcript and protein levels of auxin efflux transporter PIN-FORMED 1 (PIN1) in ceh1 seedlings grown in white light.…”

“…We further demonstrated that stress-induced MEcPP accumulation leads to growth retardation and induction of selected nuclear encoded stress response genes (Xiao et al, 2012; Walley et al, 2015; Lemos et al, 2016; Wang et al, 2017a). We specifically established that regulation of growth is in part via MEcPP-mediated modulation of levels and distribution patterns of auxin (IAA) through dual transcriptional and post-translational regulatory inputs (Jiang et al, 2018).…”

Retrograde signalling as an informant of circadian timing

“…Methylerythritol cyclodiphosphate (MEcPP) accumulates in response to wounding or high light stress, inducing the expression of nuclear stress-responsive genes and repressing the accumulation of auxin (Xiao et al, 2012;Jiang et al, 2018). Our understanding of MEcPP is still developing, but one example of a signalling pathway repressed by MEcPP accumulation involves the transcription factor BBX19.…”