TOR acts as a metabolic gatekeeper for auxin‐dependent lateral root initiation in Arabidopsis thaliana

Abstract

Plants post-embryonic organogenesis requires matching the available metabolic resources to the developmental programs. The root system is determined by the formation of lateral roots (LR), which in Arabidopsis thaliana entails the auxin-induced activation of founder cells located in the pericycle. While the allocation of sugars to roots influences root branching, how sugar availability is sensed for auxin-triggered formation of LRs remains unknown.Here, we combine metabolic profiling with cell-specific genetic interference to show that LR formation is an important sink for carbohydrate accompanied by a switch to glycolysis. We show that the target-of-rapamycin (TOR) kinase is locally activated in the pericycle and the founder cells and that both chemical and genetic inhibition of TOR kinase lead to a block of LR initiation. TOR marginally affects the auxin-induced transcriptional response of the pericycle but modulates the translation of ARF19, ARF7 and LBD16, three key targets of auxin signalling. These data place TOR as a gatekeeper for post-embryonic LR formation that integrates local auxin-dependent pathways with systemic metabolic signals, modulating the translation of auxin induced gene expression.

SPATULA as a Versatile Tool in Plant: The Progress and Perspectives of SPATULA (SPT) Transcriptional Factor

“…Auxin also regulates the formation of plant lateral roots. For example, the formation of plant lateral roots also requires the activation of auxin-dependent transcription factors ARF7, ARF19, and LBD16 [113]. Auxin signaling is also involved in regulating cambium, the stem cell niche that mediates wood formation [114].…”

A matter of perspective : Root adaptive responses to endoparasitic cystnematodes

“…WOX11-adventitious lateral roots emerge in proximity or adjacent to nematode syncytia (Golinowski et al, 1996;Willig et al, 2023a). As adventitious lateral roots are both strong sinks of assimilates (Stitz et al, 2023) and an additional source of water and minerals (Levin et al, 2020), we hypothesized that they could either compete or support syncytium hypertrophy and nematode fecundity. To test this, we counted 4 the number of adventitious lateral roots emerging from 28 dpi syncytia in Col-0, 35S::WOX11-SRDX, and lbd16-2 and performed a correlation analysis with female and syncytium size.…”

“…The presence of WOX11-mediated adventitious lateral roots at nematode infection sites might interfere with the flow of assimilates and water towards the syncytium, with possible consequences on syncytium hypertrophy and female fecundity. Indeed, similarly to syncytia, adventitious lateral roots constitute a sink of assimilates for the plant (Hofmann et al, 2007;Stitz et al, 2023). As such, adventitious lateral roots may compete with syncytia for the uptake of sucrose.…”

“…for shoot-derived carbon sources (Stitz et al, 2023). Consequently, adventitious lateral root formation may benefit syncytia by enhancing the overall availability of sucrose in the roots.…”

“…WOX11-mediated developmental plasticity is modulated by the nutritional status of the plant. Plants can perceive energy availability through sensor kinases and thereby initiate developmental programs (Stitz et al, 2023). For instance, the presence of sucrose activates the kinase TOR, which in turn regulates the translation of ARF7, ARF19, and LBD16 to promote lateral root formation.…”