Institutional Publications
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Item Paradigm and framework of WUS-CLV feedback loop in stem cell niche for SAM maintenance and cell identity transition(MDPI AG, 2022) Agarwal, Yamini; Shukla, Bhavya; Manivannan, Abinaya; Soundararajan, PrabhakaranShoot apical meristem (SAM) consists of stem cells that act as a reservoir for the aerial growth. It plays an important role in the differential architectural development in plants. SAM actively performs parallel functions by maintaining the pluripotent of stem cells and continuous organogenesis throughout the plant’s life cycle. Molecular mechanisms regulating the signaling networks of this dual function of the SAM have been progressively understood. In the SAM, the feedback loop of WUSCHEL (WUS)-CLAVATA (CLV) has been found to be the key regulator in stabilizing stem cell proliferation and differentiation. In general, WUS migrates into central zone (CZ) from organizing center (OC) and activates the expression of CLV3 by binding to the promoter elements. CLV3 acts as a ligand to interact with the CLV1, leucine rich repeats (LRR) receptor-like kinase (RLK) and LRR receptor-like protein CLV2, and protein kinase coryne (CRN) (CLV2/CRN) to restrict WUS transcription to the OC. Evolution of CLV3 is one of the main factors contributing to the transformation of two dimensional (2D) to 3D plants. WUS-CLV loop is involved in several pathways and networks that integrate on meristem maintenance and cell identity transition. WUSCLV maintains stem cells with simultaneous differentiation signals by the spatial-temporal signaling of the phytohormones. WUS-CLV loop has an interaction with reactive oxygen species (ROS), an important signaling molecules regulating cell proliferation and developmental transition. WUS also forms feedback loop with AGAMOUS (AG) for differentiation, proliferation, and termination of floral meristem. These loops might also involve in interaction with vernalization and its regulatory factors that oversees the precise timing of flowering after exposure to cold temperatures. In this review, we highlight the evolutionary and developmental importance of the WUS-CLV feedback loop on SAM maintenance and cell identity transition for inflorescence and floral meristem development.Item Potassium (K+) transporters in plants: Regulation and functional role in K+ uptake and homeostasis(Elsevier B.V., 2022) Ankit; Singh, AmarjeetPotassium (K+) is an essential macronutrient for plants and plays an important role in various cellular processes in plants. K+ transporters and channels are responsible for K+ uptake, translocation, as well as maintaining its homeostasis in plants. Other than transportation, these K+ transporters and channels are involved in other physiological processes. Several studies have shown differential expression for K+ transporter genes under abiotic stresses, such as salinity and drought. Plants can sense K+ deficiency through different mechanisms. K+ transporters and channels activity have been regulated by transcriptional as well as post–transcriptional modifications. This chapter discusses various K+ transporters and channels, their function, regulation at different levels, and their role in biotic and abiotic stress responses in plants.Item Plant phospholipase D: novel structure, regulatory mechanism, and multifaceted functions with biotechnological application(Taylor & Francis Group, 2022) Deepika, Deepika; Singh, AmarjeetPhospholipases D (PLDs) are important membrane lipid-modifying enzymes in eukaryotes. Phosphatidic acid, the product of PLD activity, is a vital signaling molecule. PLD-mediated lipid signaling has been the subject of extensive research leading to discovery of its crystal structure. PLDs are involved in the pathophysiology of several human diseases, therefore, viewed as promising targets for drug design. The availability of a eukaryotic PLD crystal structure will encourage PLD targeted drug designing. PLDs have been implicated in plants response to biotic and abiotic stresses. However, the molecular mechanism of response is not clear. Recently, several novel findings have shown that PLD mediated modulation of structural and developmental processes, such as: stomata movement, root growth and microtubule organization are crucial for plants adaptation to environmental stresses. Involvement of PLDs in regulating membrane remodeling, auxin mediated alteration of root system architecture and nutrient uptake to combat nitrogen and phosphorus deficiencies and magnesium toxicity is established. PLDs via vesicle trafficking modulate cytoskeleton and exocytosis to regulate self-incompatibility (SI) signaling in flowering plants, thereby contributes to plants hybrid vigor and diversity. In addition, the important role of PLDs has been recognized in biotechnologically important functions, including oil/TAG synthesis and maintenance of seed quality. In this review, we describe the crystal structure of a plant PLD and discuss the molecular mechanism of catalysis and activity regulation. Further, the role of PLDs in regulating plant development under biotic and abiotic stresses, nitrogen and phosphorus deficiency, magnesium ion toxicity, SI signaling and pollen tube growth and in important biotechnological applications has been discussed.Item Calcium dependent protein kinase, a versatile player in plant stress management and development(Taylor & Francis Group, 2018) Singh, Amarjeet; Sagar, Sushma; Biswas, Dipul KumarCalcium-dependent protein kinases (CDPKs) form the major and unique group of calcium (Ca2+) sensors in plants. Attributed to their peculiar structural features, CDPKs play a dual role of “Ca2+ sensor and responder” and translate the message from specific Ca2+ signature to phosphorylation events. Most of the stress and developmental triggers instigate an increase in Ca2+ level and consequently Ca2+ signaling in plants. Expression and functional analyses across plant species have revealed differential regulation of CDPK transcripts, activity, protein interactions and substrate targeting under different cues, including biotic and abiotic stresses and plant development. Thus, vital roles of CDPKs are proposed in perpetuating stress and development triggered Ca2+ signaling to adaptive responses in plants. Genetic engineering using CDPK genes could be utilitarian in the agricultural biotechnology for imparting higher degree of biotic and abiotic stress tolerance and better productivity. Here, we discuss the recent advancements and update of CDPK gene family organization, domain structure and regulatory mechanism, the role of CDPKs in abiotic stress, biotic stress, development signaling and responses in the model and crop plants.Item Over-expression of OsHOX24 confers enhanced susceptibility to abiotic stresses in transgenic rice via modulating stress-responsive gene expression(Frontiers Media S.A., 2017) Bhattacharjee, Annapurna; Sharma, Raghvendra; Jain, MukeshHomeobox transcription factors play critical roles in plant development and abiotic stress responses. In the present study, we raised rice transgenics over-expressing stress-responsive OsHOX24 gene (rice homeodomain-leucine zipper I sub-family member) and analyzed their response to various abiotic stresses at different stages of development. At the seed germination stage, rice transgenics over-expressing OsHOX24 exhibited enhanced sensitivity to abiotic stress conditions and abscisic acid as compared to wild-type (WT). OsHOX24 over-expression rice seedlings showed reduced root and shoot growth under salinity and desiccation stress (DS) conditions. Various physiological and phenotypic assays confirmed higher susceptibility of rice transgenics toward abiotic stresses as compared to WT at mature and reproductive stages of rice development too. Global gene expression profiling revealed differential regulation of several genes in the transgenic plants under control and DS conditions. Many of these differentially expressed genes were found to be involved in transcriptional regulatory activities, besides carbohydrate, nucleic acid and lipid metabolic processes and response to abiotic stress and hormones. Taken together, our findings highlighted the role of OsHOX24 in regulation of abiotic stress responses via modulating the expression of stress-responsive genes in rice.Item Regulation of MAP kinase signaling cascade by microRNAs in Oryza sativa(Taylor & Francis Group, 2014) Raghuram, Badmi; Sheikh, Arsheed Hussain; Sinha, Alok KrishnaMitogen activated protein kinase (MAPK) pathway is one of the most conserved signaling cascade in plants regulating a plethora of cellular processes including normal growth and development, abiotic and biotic stress responses. The perception of external cues triggers the phosphorylation of three tier MAPKKK-MAPKK-MAPK cascade which finally modifies a downstream substrate thereby regulating the cellular processes. Whereas, the transcription regulation by MAPKs, mediated through their substrates is well studied in plants, the transcription and post-transcriptional regulation of the MAPK genes are poorly understood. Previous studies from the animals systems suggested the miRNAs regulate the post-transcriptional regulation of MAPK transcripts. Here we attempt to unravel the post-transcriptional regulation of MAPKs by miRNAs in model crop plant Oryza sativa. Using in silico tools, we predict the miRNAs for 98 out of 99 MAPK transcripts. The predicted miRNAs were validated for the biological relevance of their function. The inverse correlation between relative transcript levels between the MAPKs and their predicted miRNAs validated the in silico prediction. Taken together, this report demonstrates the significance of miRNAs in regulation of the MAPK pathway in plants with a new direction to study the plant signaling molecules.