Publications of NIPGR Scientists
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Item Rooted in communication: Exploring auxin-salicylic acid nexus in root growth and development(John Wiley & Sons, 2025) Rawat, Sanjay Singh; Laxmi, AshveryaPlant hormones are pivotal in orchestrating diverse aspects of growth and developmental processes. Among various phytohormones, auxin and salicylic acid (SA) stand out as important regulators, often exerting opposing effects on overall plant growth. Essentially, research has indicated that auxin and SA-mediated pathways exhibit mutual antagonism during pathogen challenge. Additionally, in recent years, significant advancements have been made in uncovering the molecular intricacies that govern the action and interplay between these two phytohormones during various essential growth-related processes. In this discussion, we briefly delve into the genetic and molecular mechanisms involved in auxin and SA antagonism. We then analyse in detail how this dialogue impacts critical aspects of root development, with an emphasis on the transcriptional and protein regulatory networks. Finally, we propose the potential of exploring their interaction in various other aspects of below ground root growth processes. Understanding this relationship could provide valuable insights for optimizing and enhancing crop growth and yields.Item MEDIATOR SUBUNIT17 integrates jasmonate and auxin signaling pathways to regulate thermomorphogenesis(Oxford University Press, 2022) Agrawal, Rekha; Sharma, Mohan; Dwivedi, Nidhi; Maji, Sourobh; Thakur, Pallabi; Junaid, Alim; Fajkus, Jiří; Laxmi, Ashverya; Thakur, Jitendra K.Plant adjustment to environmental changes involves complex crosstalk between extrinsic and intrinsic cues. In the past two decades, extensive research has elucidated the key roles of PHYTOCHROME INTERACTING FACTOR4 (PIF4) and the phytohormone auxin in thermomorphogenesis. In this study, we identified a previously unexplored role of jasmonate (JA) signaling components, the Mediator complex, and their integration with auxin signaling during thermomorphogenesis in Arabidopsis (Arabidopsis thaliana). Warm temperature induces expression of JA signaling genes including MYC2, but, surprisingly, this transcriptional activation is not JA dependent. Warm temperature also promotes accumulation of the JA-signaling receptor CORONATINE INSENSITIVE1 (COI1) and degradation of the JA-signaling repressor JASMONATE-ZIM-DOMAIN PROTEIN9 (JAZ9), which probably leads to de-repression of MYC2, enabling it to contribute to the expression of MEDIATOR SUBUNIT17 (MED17). In response to warm temperature, MED17 occupies the promoters of thermosensory genes including PIF4, YUCCA8 (YUC8), INDOLE-3-ACETIC ACID INDUCIBLE19 (IAA19), and IAA29. Moreover, MED17 facilitates enrichment of H3K4me3 on the promoters of PIF4, YUC8, IAA19, and IAA29 genes. Interestingly, both occupancy of MED17 and enrichment of H3K4me3 on these thermomorphogenesis-related promoters are dependent on PIF4 (or PIFs). Altered accumulation of COI1 under warm temperature in the med17 mutant suggests the possibility of a feedback mechanism. Overall, this study reveals the role of the Mediator complex as an integrator of JA and auxin signaling pathways during thermomorphogenesis.Item Genome-wide identification and expression, protein-protein interaction and evolutionary analysis of the seed plant-specific BIG GRAIN and BIG GRAIN LIKE gene family(Frontiers Media S.A., 2017) Mishra, Bhuwaneshwar S.; Jamsheer, K Muhammed; Singh, Dhriti; Sharma, Manvi; Laxmi, AshveryaBIG GRAIN1 (BG1) is an auxin-regulated gene which functions in auxin pathway and positively regulates biomass, grain size and yield in rice. However, the evolutionary origin and divergence of these genes are still unknown. In this study, we found that BG genes are probably originated in seed plants. We also identified that seed plants evolved a class of BIG GRAIN LIKE (BGL) genes which share conserved middle and C-terminal motifs with BG. The BG genes were present in all monocot and eudicot species analyzed; however, the BGL genes were absent in few monocot lineages. Both BG and BGL were found to be serine-rich proteins; however, differences in expansion and rates of retention after whole genome duplication events were observed. Promoters of BG and BGL genes were found to be enriched with auxin-responsive elements and the Arabidopsis thaliana BG and BGL genes were found to be auxin-regulated. The auxin-induced expression of AthBG2 was found to be dependent on the conserved ARF17/19 module. Protein-protein interaction analysis identified that AthBG2 interact with regulators of splicing, transcription and chromatin remodeling. Taken together, this study provides interesting insights about BG and BGL genes and incentivizes future work in this gene family which has the potential to be used for crop manipulation.Item Ethylene acts as a negative regulator of glucose induced lateral root emergence in Arabidopsis(Taylor & Francis Group, 2015) Singh, Manjul; Gupta, Aditi; Laxmi, AshveryaPlants, being sessile organisms, are more exposed to the hazards of constantly changing environmental conditions globally. During the lifetime of a plant, the root system encounters various challenges such as obstacles, pathogens, high salinity, water logging, nutrient scarcity etc. The developmental plasticity of the root system provides brilliant adaptability to plants to counter the changes exerted by both external as well as internal cues and achieve an optimized growth status. Phytohormones are one of the major intrinsic factors regulating all aspects of plant growth and development both independently as well as through complex signal integrations at multiple levels. We have previously shown that glucose (Glc) and brassinosteroid (BR) signalings interact extensively to regulate lateral root (LR) development in Arabidopsis. (1) Auxin efflux as well as influx and downstream signaling components are also involved in Glc-BR regulation of LR emergence. Here, we provide evidence for involvement of ethylene signaling machinery downstream to Glc and BR in regulation of LR emergence.Item Role of CIPK6 in root growth and auxin transport(Landes Bioscience, 2009) Tripathi, Vineeta; Syed, Nazia; Laxmi, Ashverya; Chattopadhyay, DebasisIn our recent publication,1 we have shown that a T-DNA insertion in Arabidopsis CIPK6 gene encoding a CBL-interacting protein kinase caused reduction in expression of the gene and emergence of lateral roots. The change in phenotype in the mutant line was likely due to reduction in shoot-to-root acro- petal and the root tip basipetal auxin transport. Here we report identification of a homozygous knockout line of AtCIPK6 (atcipk6) with no detectable expression of the gene in normal growth condition. The knockout line exhibited considerable decrease in growth rate of the taproot as well as in emergence of lateral roots. The mutant line also showed reduction in the root tip basipetal and shoot-to-root acropetal auxin transport. Relative rate of auxin transport and the root phenotype of the atcipk6 closely matched with those of pgp4-1, an Arabidopsis line mutated in PGP4. This gene encodes an ABC integral membrane transporter, which functions in polar auxin transport. These observations strengthen our earlier proposal that CIPK6 is probably involved in polar auxin transport and indicate that it may function through the PGP4 auxin transporter.Item CIPK6, a CBL-interacting protein kinase is required for development and salt tolerance in plant(Wiley-Blackwell, 2009) Tripathi, Vineeta; Parasuraman, Boominathan; Laxmi, Ashverya; Chattopadhyay, DebasisCalcineurin B-like proteins (CBL) and CBL-interacting protein kinases (CIPK) mediate plant responses to a variety of external stresses. Here we report that Arabidopsis CIPK6 is also required for the growth and development of plants. Phenotype of tobacco plants ectopically expressing a homologous gene (CaCIPK6) from the leguminous plant chickpea (Cicer arietinum) indicated its functional conservation. A lesion in AtCIPK6 significantly reduced shoot-to-root and root basipetal auxin transport, and the plants exhibited developmental defects such as fused cotyledons, swollen hypocotyls and compromised lateral root formation, in conjunction with reduced expression of a number of genes involved in auxin transport and abiotic stress response. The Arabidopsis mutant was more sensitive to salt stress compared to wild-type, while overexpression of a constitutively active mutant of CaCIPK6 promoted salt tolerance in transgenic tobacco. Furthermore, tobacco seedlings expressing the constitutively active mutant of CaCIPK6 showed a developed root system, increased basipetal auxin transport and hypersensitivity to auxin. Our results provide evidence for involvement of a CIPK in auxin transport and consequently in root development, as well as in the salt-stress response, by regulating the expression of genes.Item Role of glucose in spatial distribution of auxin regulated genes(Landes Bioscience, 2009) Gupta, Aditi; Singh, Manjul; Mishra, Bhuwaneshwar S.; Kushwah, Sunita; Laxmi, AshveryaPlants have the ability to adjust its physiology and metabolism to the changes of nutrient availability in the environment. Since a number of common responses are regulated by sugar and auxin, the obvious question arises is whether sugar and auxin act interdependently to bring about changes in plant morphology. In the February issue of the PLoS ONE,1 we presented detailed investigation of glucose and auxin signaling interaction in controlling root growth and development in Arabidopsis thaliana seedlings. Further analysis of tissue specific regulation of glucose auxin signaling interaction may provide some insight as to how these two signaling molecules interact to control the morphogenic changes during seedling development.