Browsing by Author "Awasthi, Prakhar"

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Arabidopsis target of rapamycin coordinates with transcriptional and epigenetic machinery to regulate thermotolerance
(Frontiers Media S.A., 2021) Sharma, Mohan; Jamsheer, K.M.; Shukla, Brihaspati Narayan; Sharma, Manvi; Awasthi, Prakhar; Mahtha, Sanjeet Kumar; Yadav, Gitanjali; Laxmi, Ashverya
Global warming exhibits profound effects on plant fitness and productivity. To withstand stress, plants sacrifice their growth and activate protective stress responses for ensuring survival. However, the switch between growth and stress is largely elusive. In the past decade, the role of the target of rapamycin (TOR) linking energy and stress signalling is emerging. Here, we have identified an important role of Glucose (Glc)-TOR signalling in plant adaptation to heat stress (HS). Glc via TOR governs the transcriptome reprogramming of a large number of genes involved in heat stress protection. Downstream to Glc-TOR, the E2Fa signalling module regulates the transcription of heat shock factors through direct recruitment of E2Fa onto their promoter regions. Also, Glc epigenetically regulates the transcription of core HS signalling genes in a TOR-dependent manner. TOR acts in concert with p300/CREB HISTONE ACETYLTRANSFERASE1 (HAC1) and dictates the epigenetic landscape of HS loci to regulate thermotolerance. Arabidopsis plants defective in TOR and HAC1 exhibited reduced thermotolerance with a decrease in the expression of core HS signalling genes. Together, our findings reveal a mechanistic framework in which Glc-TOR signalling through different modules integrates stress and energy signalling to regulate thermotolerance.
Balancing growth and defense: Role of target of rapamycin and SNF1-related protein kinase 1 in stress signaling in plants
(John Wiley & Sons, 2021) Sharma, Mohan; Jamsheer, K. Muhammed; Saksena, Harshita B.; Jindal, Sunita; Sharma, Manvi; Singh, Dhriti; Tiwari, Archna; Awasthi, Prakhar; Laxmi, Ashverya
Plants have to maintain the growth and at the same time need to be vigilant about the imminent threat such as pathogen attack and unfavorable growth conditions. It is been observed that the energy status of the plant is an important determinant of the response to stress factors. The Target Of Rapamycin (TOR) and SNF1-Related Protein Kinase 1 (SnRK1) are serine/threonine kinases that originated early in the eukaryotic evolution, work as energy gauges in all eukaryotic lineages. During favorable growth conditions, the nutrient abundance activates TOR, which promotes growth through activation of general protein translation and cell cycle progression. The stress conditions can severely limit energy production, which can activate SnRK1 signaling. By inhibiting TOR kinase and through other effector proteins, the SnRK1 pathway enables the plants to survive in unfavorable growth conditions. The past decade opened a floodgate of studies regarding TOR and SnRK1 interaction regulating growth-defense trade-offs and stress mitigation. This also opened avenues for the utilization of these pathways for crop improvement. This chapter will succinctly summarize the current knowledge in this field and discuss the future direction of research.
The confluence of TOR signaling and plant growth regulators in development and stress responses
(Oxford University Press, 2026) Saksena, Harshita B; Kumar, Mukesh; Samtani, Harsha; Sharma, Aishwarye; Rawat, Sanjay Singh; Awasthi, Prakhar; Botta, Halidev Krishna; Sandhya, Shital; Pande, Anjali; Naaz, Sheeba; Kushwah, Sunita; Shukla, Brihaspati N; Laxmi, Ashverya
The Target of Rapamycin (TOR) is an evolutionarily conserved protein kinase that serves as a crucial signaling hub, seamlessly integrating a wide range of internal and external signals to meticulously regulate cellular and organismal physiology. TOR is crucial in regulating the different phases of lifecycle in plants including embryogenesis, seed germination, meristem activation, root and leaf development, flowering and senescence. Beyond its central role in growth and development, emerging research has revealed its significant involvement in the response to environmental stresses. Even though plant growth regulators such as auxin, cytokinin (CK), brassinosteroid (BR), gibberellin (GA), abscisic acid (ABA), ethylene (ET), salicylic acid (SA), jasmonic acid (JA) and nitric oxide (NO) function as pivotal signaling molecules in modulating plant development and stress responses, how they coordinate with the energy status still remains obscure. Here we summarize the current findings on the dynamic interconnection between TOR and these discrete phytoregulators and their potential role in executing diverse biological processes in plants.
A negative feedback loop of TOR signaling balances growth and stress-response trade-offs in plants
(Cell Press, 2022) Jamsheer, Muhammed K; Jindal, Sunita; Sharma, Mohan; Awasthi, Prakhar; S, Sreejath; Sharma, Manvi; Mannully, Chanchal Thomas; Laxmi, Ashverya
TOR kinase is a central coordinator of nutrient-dependent growth in eukaryotes. Maintaining optimal TOR signaling is critical for the normal development of organisms. In this study, we describe a negative feedback loop of TOR signaling helping in the adaptability of plants in changing environmental conditions. Using an interdisciplinary approach, we show that the plant-specific zinc finger protein FLZ8 acts as a regulator of TOR signaling in Arabidopsis. In sugar sufficiency, TOR-dependent and -independent histone modifications upregulate the expression of FLZ8. FLZ8 negatively regulates TOR signaling by promoting antagonistic SnRK1α1 signaling and bridging the interaction of SnRK1α1 with RAPTOR1B, a crucial accessory protein of TOR. This negative feedback loop moderates the TOR-growth signaling axis in the favorable condition and helps in the activation of stress signaling in unfavorable conditions, establishing its importance in the adaptability of plants.
The social network of target of rapamycin complex 1 in plants
(Oxford University Press, 2022) Jamsheer, Muhammed K; Awasthi, Prakhar; Laxmi, Ashverya
The Target Of Rapamycin Complex 1 (TORC1) is a highly conserved serine-threonine protein kinase crucial for coordinating growth according to nutrient availability in eukaryotes. TORC1 works as a central integrator of multiple nutrient inputs such as sugar, nitrogen, and phosphate and promotes growth and biomass accumulation in response to nutrient sufficiency. Studies especially in the past decade identified the central role of TORC1 in regulating growth through interaction with hormones, photoreceptors, and stress signaling machinery in plants. In this review, we comprehensively analyzed the interactome and phosphoproteome of the Arabidopsis TORC1 signaling network. Our analysis highlights the role of TORC1 as a central hub kinase communicating with transcriptional and translational apparatus, ribosomes, chaperones, protein kinases, metabolic enzymes, and autophagy and stress response machinery to orchestrate growth in response to the nutrient signals. This analysis also suggests that along with the conserved downstream components shared with other eukaryotic lineages, the plant TORC1 signaling underwent several evolutionary innovations and coopted many lineage-specific components during the plant evolution. Based on the protein-protein interaction and phosphoproteome data, we also discuss several uncharacterized and unexplored components of the TORC1 signaling network highlighting potential links for future studies.
Sweet shaping of root system architecture under water deficit
(Oxford University Press, 2026) Singh, Dhriti; Awasthi, Prakhar; Sharma, Aishwarye; Samtani, Harsha; Shukla, Brihaspati Narayana; Laxmi, Ashverya
Root growth direction under water-deficit conditions is critical for plant survival. Increasing agar concentration in the growth medium simulates stress conditions, limiting water availability. Our study highlights the role of glucose (Glc) in orchestrating the root growth deviation in Arabidopsis under stress conditions. We demonstrate that Glc-TOR signaling plays a central role in modulating root growth direction under stress conditions. Conversely, cytokinin (CK) signaling reduces root deviation during water deficit. We further show that Glc downregulates CK signaling under water-deficit conditions, while CK negatively influences Glc–TOR activity. The interplay between Glc-TOR and CK signaling pathways fine-tunes root orientation by modulating auxin transport and signaling. Collectively, our findings show that in Arabidopsis, Glc-induced changes in root architecture are mediated through its antagonistic interaction with CK signaling, contributing to enhanced root plasticity and improved adaptation to water-limited conditions.
Understanding the intricate web of phytohormone signalling in modulating root system architecture
(MDPI AG, 2021) Sharma, Manvi; Singh, Dhriti; Saksena, Harshita B.; Sharma, Mohan; Tiwari, Archna; Awasthi, Prakhar; Botta, Halidev Krishna; Shukla, Brihaspati Narayan; Laxmi, Ashverya
Root system architecture (RSA) is an important developmental and agronomic trait that is regulated by various physical factors such as nutrients, water, microbes, gravity, and soil compaction as well as hormone-mediated pathways. Phytohormones act as internal mediators between soil and RSA to influence various events of root development, starting from organogenesis to the formation of higher order lateral roots (LRs) through diverse mechanisms. Apart from interaction with the external cues, root development also relies on the complex web of interaction among phytohormones to exhibit synergistic or antagonistic effects to improve crop performance. However, there are considerable gaps in understanding the interaction of these hormonal networks during various aspects of root development. In this review, we elucidate the role of different hormones to modulate a common phenotypic output, such as RSA in Arabidopsis and crop plants, and discuss future perspectives to channel vast information on root development to modulate RSA components.