Figure 7. Target of Rapamycin (TOR) kinase is a positive regulator of plant fatty acid and lipid synthesis.
Plant TOR is activated by light and sugars. Once activated, TOR positively regulates fatty acid (FA) and lipid synthesis by upregulating genes involved in de novo fatty acid synthesis and downregulating genes associated with lipid turnover. Additionally, TOR promotes the biosynthesis of proteins, cell walls, DNA, RNA, and the other essential cellular components.
TOR complex shown in the figure is comprising of LST8-1 (Lethal with SEC13 protein 8-1, in green), TOR (in purple) and RAPTOR1B (Regulatory-associated protein of TOR 1B, in yellow) and its 3D structure model is predicated by AlphaFold 3.
Figure 1. Transient expression of TOR in Nicotiana benthamiana (N. benth) leaves increases the levels of total fatty acids (TFAs).
A) Representative fluorescence confocal image of N. benth leaf samples taken 4 days after agroinfiltration with TOR-GFP. Bar = 50 µm.
B) Immunoblotting with anti-GFP antibody shows TOR-GFP is detected in protein samples extracted from N. benth leaves 4 days after infiltration with agrobacterium containing plasmid TOR/pCHF3-hGFP (TOR-GFP), but not pCHF3-hGFP (Empty vector, EV). Ponceau S staining of PVDF membrane after protein transfer is shown as a protein loading control. M, protein markers. Multiple lanes for the same construct represent biological replicates.
C) Transient expression of TOR for 4 days after agroinfiltration significantly elevates total fatty acids content in N. benth leaves after. Bar values represent mean ± SD (n = 6), with each data point represented by a dot. Asterisks denote a statistically difference from the EV (Student's t-test, **, P < 0.01).
Figure 5. Suppression of TOR activity by Torin 2 in a Brassica napus suspension cell culture results in significant reduction in the accumulation of both total fatty acid (TFA) and triacylglycerol (TAG).
A) TFA content in Brassica napus microspore-derived suspension cells cultured in medium supplemented without (−) or with (+) 1 μM Torin 2 for the indicated time periods.
B) TAG content in the Brassica napus suspension cells in (A). In this figure, bar values represent mean ± SD (n = 4), with each data point represented by a dot. Asterisks denote statistically significant differences from the non-Torin 2 treatment controls (Student’s t-test, *, P < 0.05; ***, P < 0.001).
Great work by Liu et al. (2024) on how #PlantTOR kinase positively regulates plant #FattyAcid and lipid synthesis in #Nicotiana benthamiana leaves 🍃, #Arabidopsis seedlings 🌱 and #Brassica napus suspension cells.
PS. Relatively short periods were used for the assays.
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