Artins, A. | Search bioRxiv

bioRxiv2023

FCS-Like Zinc finger 14 (FLZ14) mediates the crosstalk between TORC and SnRK1 in response to sugar availability.

Matching resource availability to growth is crucial for plant fitness. We identified that FCS- Like Zinc finger 14 (FLZ14) gauges carbon (C) status to adjust growth by inhibiting the TARGET OF RAPAMYCIN (TOR) activity in short days via REGULATORY- ASSOCIATED PROTEIN OF TARGET OF RAPAMYCIN 1B (RAPTOR1B). Besides being transcriptionally induced by sugars, the amplitude of FLZ14 induction correlates to the diel sugar status, indicating that FLZ14 responses to sugar oscillations in planta. Genetic evidence elucidated that FLZ14 is involved in the crosstalk between TORC and SUCROSE NON-FERMENTING RELATED KINASE 1 (SnRK1). In short photoperiods, FLZ14 and KIN10 genetically interact to set the pace of TORC activity. By contrast, under long day photoperiods, FLZ14 and RAPTOR1B genetically interact, most likely to downregulate SnRK1 signalling. This report highlights the function of a sugar-responsive gene in mediating the crosstalk between TORC and SnRK1 to fine-tune growth.

plant biology↗

bioRxiv2022

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

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.

plant biology↗