Biology subjects

Jamsheer K, M.

Publications and source records attributed to Jamsheer K, M..

5 recordsLinked to original sources

bioRxiv2025

Integrative transcriptomic and phosphoproteomic analysis reveals key components of SnRK1 signaling network in rice

SnRK1 is an evolutionarily conserved protein kinase belonging to SNF1/AMPK family of protein kinases that is central to adjusting growth in response to the energy status. Numerous studies have shown adaptive and developmental roles of SnRK1, but the understanding of SnRK1 signaling network in monocots is limited. Using CRISPR/Cas9 mutagenesis to target the functional kinase subunits in rice, we carried out a comprehensive phenotypic, transcriptomic, proteomic, and phosphoproteomic analyses of rice snrk1 mutants displaying growth defects under normal and starvation conditions. These analyses revealed the role of SnRK1 signaling in controlling growth and stress-related processes in both energy-sufficient and energy-limited conditions and pointed to sub-functionalization of SnRK1 kinase subunit genes. In addition to the classical protein targets of SnRK1, phosphoproteomics revealed novel targets including the key components of intracellular membrane trafficking, ethylene signaling, and ion transport. The upregulation of stress-related processes and suppression of growth-related processes in snrk1 mutants correlated with their phenotypic defects. Overall, this study highlights the dual role of SnRK1 as promoter of growth under favorable conditions and critical regulator of adaptive response under stress conditions.

plant biology↗

bioRxiv2024

A TORC1-PHR1 signaling axis regulates phosphorus starvation and immunity signaling network in Arabidopsis

The Target of Rapamycin Complex 1 (TORC1) is a crucial eukaryotic kinase that modulates growth in response to nutrient availability. Phosphorus (P) is an essential macronutrient, and its deficiency induces extensive reprogramming of growth and defense strategies in plants. This process involves Phosphate Starvation Response 1 (PHR1), a master regulator of the Phosphate Starvation Response (PSR). In this study, we identify a novel, non-canonical role for TORC1 in regulating P starvation responses in Arabidopsis. We demonstrate that P limitation activates TORC1, leading to the stabilization of PHR1. Inhibition of TORC1 increased sensitivity to P starvation, accompanied by disruption of starvation-induced transcriptional reprogramming. Additionally, our results reveal that the TORC1-PHR1 signaling axis plays a crucial role in reprogramming the expression of genes involved in the plant immune signaling network. This regulation is critical for the symbiotic association with the endophytic fungus Piriformospora indica under P starvation. These findings underscore the significant role of the TORC1-PHR1 module in orchestrating the PSR and highlight the evolutionary adaptation of TORC1 signaling pathways in plants.

plant biology↗

bioRxiv2022

Stepwise origin and evolution of a transcriptional activator and repressor system integrating nutrient signaling in plants

Plants possess a unique transcriptional regulatory system in which two related MYB-related transcription factors (TFs) coordinate gene expression according to phosphate (Pi) and nitrogen (N) availability. The Phosphorus Starvation Response (PSR) type TFs are transcriptional activators integrating the cellular Pi sensing machinery and gene regulation majorly under Pi starvation. The Hypersensitivity To Low Pi-Elicited Primary Root Shortening (HRS) type TFs are transcriptional repressors integrating the Pi and N availability signals through different feedback loops. They are highly connected through multiple signaling loops to finetune the transcriptional responses according to nutrient availability. Molecular functions of these TFs are fairly uncovered in model systems; however, how plants evolved this activator-repressor system is currently unknown. In this study, using sensitive evolutionary analysis, we identified a stepwise origin of the PSR-HRS regulatory system in plants. The PSR TFs were originated before the split of Prasinodermophyta and Chlorophyta. The HRS TFs were originated later in the Streptrophycean algae. We also identified the asymmetric expansion of this TF repertoire in land plants majorly shaped by genome duplication and triplication events. The phylogenetic reconstruction coupled with motif analysis revealed that the origin of the specific accessory motifs is a major contributing factor in the functional divergence which led to the evolution of different sub-families preceding the angiosperm radiation. The spatiotemporal gene expression analysis in different developmental stages and nutrient availability conditions in angiosperms identified a critical role of expression divergence in shaping the functions of these TF families which is essential for adaptive plasticity of plants.

plant biology↗

bioRxiv2020

A negative feedback loop of the TOR signaling moderates growth and enables rapid sensing of stress signals in plants

TOR kinase is a central coordinator of nutrient-dependent growth in eukaryotes. Maintaining optimal TOR signaling is critical for the normal development of organisms. However, the mechanisms involved in the maintenance of optimal TOR signaling are currently unknown in plants. 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 identified a plant-specific zinc finger protein FLZ8, as a regulator of TOR signaling in Arabidopsis. In sugar sufficiency, FLZ8 is upregulated by TOR-dependent and -independent histone modifications. FLZ8 negatively regulates TOR signaling by promoting antagonistic SnRK11 signaling and bridging the interaction of SnRK11 with RAPTOR, a crucial accessory protein of TOR. This negative feedback loop moderates the TOR-growth signaling axis in the favorable condition and helps in the rapid activation of stress signaling in unfavorable conditions establishing its importance in the adaptability of plants.

plant biology↗

bioRxiv2020

Jasmonic acid coordinates with light to regulate branching angle of Arabidopsis lateral roots

The role of jasmonates (JAs) in primary root growth and development and in plant response to external stimuli is already known. However, its role in lateral root (LR) development remains to be explored. Our work identified methyl jasmonate (MeJA) as a key phytohormone in determining the branching angle of Arabidopsis LRs. MeJA inclines the LRs to a more vertical orientation, which was dependent on the canonical JAR1-COI1-MYC2, 3, 4 signalling. Our work also highlights the dual roles of light in governing LR angle. Light signalling enhances JA biosynthesis, leading to erect root architecture; whereas, glucose (Glc) induces wider branching angles. Combining physiological and molecular assays, we revealed that Glc antagonizes the MeJA response via TARGET OF RAPAMYCIN (TOR) signalling. Moreover, physiological assays using auxin mutants, MYC2-mediated transcriptional activation of LAZY2, LAZY4 and auxin biosynthetic gene CYP79B2, and asymmetric distribution of DR5::GFP and PIN2::GFP pinpointed the role of an intact auxin mechanism required by MeJA for vertical growth of LRs. We also demonstrated that light perception and signalling are indispensable for inducing vertical angles by MeJA. Thus, our investigation highlights antagonism between light and Glc signalling and how they interact with JA-auxin signals to optimize the branching angle of LRs.

plant biology↗