How plants are teaching us about TOR proteins and their impacts on the pathways.
The target of Rapamycin (TOR) present in all eukaryotes is a multifunctional protein, regulating growth, development, protein translation, ribosome biogenesis, nutrient, and energy signaling. In the present study, ectopic expression of TOR gene of Arabidopsis thaliana in a widely cultivated indica rice resulted in enhanced plant growth under water-limiting conditions conferring agronomically important water-use efficiency (WUE) trait. The AtTOR high expression lines of rice exhibited profuse tillering, increased panicle length, increased plant height, high photosynthetic efficiency, chlorophyll content and low ∆13 C. Δ13 C, which is inversely related to high WUE, was as low as 17‰ in two AtTOR high expression lines. These lines were also insensitive to the ABA-mediated inhibition of seed germination. The significant upregulation of 15 stress-specific genes in high expression lines indica tes their contribution to abiotic stress tolerance. The constitutive expression of AtTOR is also associated with significant transcriptional upregulation of putative TOR complex-1 components, Os Raptor and OsLST8. Glucose-mediated transcriptional activation of AtTOR gene enhanced lateral root formation. Taken together, our findings indica te that TOR, in addition to its multiple cellular functions, also plays an important role in response to abiotic stress and potentially enhances WUE and yield related attributes.
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