Abstract
The Target of Rapamycin (TOR) kinase pathway integrates energy and nutrient availability into metabolism promoting growth in eukaryotes. The overall higher efficiency on nutrient use translated into faster growth rates in C4 grass plants led to the investigation of differential transcriptional and metabolic responses to short-term chemical TOR complex (TORC) suppression in the model Setaria viridis. In addition to previously described responses to TORC inhibition (i.e., general growth arrest, translational repression, and primary metabolism reprogramming) in Arabidopsis thaliana (C3), the magnitude of changes was smaller in S. viridis, particularly regarding nutrient use efficiency and C allocation and partitioning that promote biosynthetic growth. Besides photosynthetic differences, S. viridis and A. thaliana present several specificities that classify them into distinct lineages, which also contribute to the observed alterations mediated by TOR. Indeed, cell wall metabolism seems to be distinctly regulated according to each cell wall type, as synthesis of non-pectic polysaccharides were affected in S. viridis, whilst assembly and structure in A. thaliana. Our results indicate that the metabolic network needed to achieve faster growth seems to be less stringently controlled by TORC in S. viridis.
Highlights
Adaptation and evolution have driven the generation of plants with different metabolism that perform better in particular environments
Sequences of the Target of Rapamycin (TOR) protein were first compared among selected photosynthetic organisms, from the green algae Chlamydomonas reinhardtii to monocots and eudicots
A slightly higher affinity of the complex to rapamycin has been previously reported for maize (Agredano-Moreno et al, 2007) as a consequence of an amino acid substitution, which is present in S. viridis FKBP12 sequence (S-55, Supplementary Figure 2A)
Summary
Adaptation and evolution have driven the generation of plants with different metabolism that perform better in particular environments. Despite the conservation of some direct TORC targets from yeasts and animals to photosynthetic organisms (De Virgilio and Loewith, 2006; Wullschleger et al, 2006; Soulard et al, 2009; Dobrenel et al, 2016a), as p70 S6 Kinase (S6K/Sch9) involved in protein translation, other targets are either missing or new regulatory steps were aggregated according to the complexity level of organisms for fine-tuning TOR activity (Henriques et al, 2014; Xiong and Sheen, 2015; Shi et al, 2018). The sessile life form of plants, besides their photoautotrophic nature, provides a special niche for the discovery of unknown mechanisms under the coordination of this pathway
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
