Publications of NIPGR Scientists

Permanent URI for this communityhttps://ndkr-library.nipgr.ac.in/handle/123456789/1

Browse

Start date: 2020Subject: search.filters.subject.Cytokinin

Search Results

Now showing 1 - 8 of 8
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    A cytokinin-auxin antagonistic module participates in nitrogen-triggered tiller outgrowth in rice
    (Oxford University Press, 2026) Chatterjee, Sourav; Dwivedi, Aditi; Sarkar, Ananda K; Ranjan, Aashish
    Tillering is a key trait that shapes rice (Oryza sativa L.) shoot architecture and directly influences yield. While tiller bud formation is largely genetically determined, bud outgrowth into functional tillers is highly responsive to environmental cues. However, integration of environmental signals with genetic regulators to determine tiller bud fate remains poorly understood. Here, we investigated the effects of nitrogen on early stages of tiller bud outgrowth. Comprehensive phenotyping and temporal transcriptomic analyses demonstrated that both nitrate and ammonium promote bud outgrowth and elicit overlapping transcriptional responses, with nitrate acting more slowly. Gene regulatory network analysis identified phytohormone signaling as a key interface for nitrogen- triggered tiller outgrowth. Pharmacological and molecular experiments demonstrated the involvement of cytokinin–auxin antagonism in nitrogen-mediated tillering. Cytokinin promoted bud activation by repressing the critical bud dormancy regulators rice TEOSINTE BRANCHED 1 (OsTB1) and a homolog of PIN-FORMED 1 (OsPIN1a) through the Cytokinin Response Factors OsERF53/54. In contrast, auxin maintained dormancy by inducing OsTB1 and OsPIN1a expression through Auxin Response Factors OsARF11/16. Consistently, OsTB1 overexpression lines showed reduced responsiveness to nitrogen and hormone treatments, placing OsTB1 downstream of these convergent inputs. Sequence and gene expression differences in OsERF53/54, along with phenotypic variations across contrasting rice accessions, further substantiated the crucial roles of OsERF53/54 in nitrogen-mediated tillering. Together, we identify a key regulatory role of the cytokinin-auxin antagonistic module for integrating nitrogen signals to determine tiller bud fate. Adequate nitrogen promotes cytokinin signaling while attenuating auxin signaling and transport in tiller buds, thereby releasing dormancy and initiating bud outgrowth.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    Host manipulations within mutualisms: Role of plant hormones in selective resource allocation
    (Springer Nature Publishing AG, 2025) Kulkarni, Manasa; Vadassery, Jyothilakshmi; Borges, Renee M.
    In some mutualisms involving host plants, photoassimilates are provided as rewards to symbionts. Endophagous organisms often manipulate host plants to increase access to photoassimilates. Host manipulations by endophagous organisms that are also mutualists are poorly understood. We show host plant manipulations by symbionts and the role of phytohormones, i.e. the auxin indole-3-acetic acid (IAA), and the cytokinin trans-zeatin (tZ), in the brood-site pollination mutualism between fig trees and pollinator fig wasps. In this interaction, pollinator wasps pollinate Ficus flowers within an enclosed inflorescence called a syconium, in exchange for flowers that develop into galls nourishing pollinator offspring. To examine host manipulation by pollinator galls by affecting host fitness through seed reduction, we compared growth hormones released by syconial occupants within three experimentally produced treatment groups of syconia: S (containing only seeds), G (containing only pollinator galls) and SG (containing seeds and pollinator galls). We harvested syconia from each treatment in early and mid-phases of syconial maturation when maximal growth occurs and measured hormone levels. Hormones were reduced by mid-phase in general; however, their levels were mostly sustained in G syconia in the mid-phase, suggesting that galls manipulate the host to continuously access resources. We found no difference in IAA and tZ levels of S and G syconia. IAA concentrations were higher in SG syconia. From the perspective of the maintenance of mutualism, syconium volume and hormone concentrations were highest when both seeds and galls were present (SG treatment), indicating that both partners control allocation of resources to syconia.
  • Thumbnail Image
    Item
    Functional characterization of WsPR-1 reveals its interplay with cytokinin and gibberellin signaling pathways
    (Elsevier B.V., 2024) Singh, Varinder; Kumar, Paramdeep; Pandey, Ashutosh; Hallan, Vipin; Pati, Pratap Kumar
    Pathogenesis-related protein 1 (PR-1) is an antimicrobial protein involved in systemic acquired resistance (SAR) in plants, but its regulatory role and interactions with other pathways remain unclear. In this study, we functionally characterize WsPR-1 gene of Withania somnifera in Nicotiana tabacum to elucidate its role in plant defense, growth, and development. Interestingly, transgenic tobacco plants with increased levels of cytokinin (CK) and decreased gibberellins (GAs) exhibited stunted shoot growth, an underdeveloped root system, modified leaf morphology, reduced seed pod production, and delayed leaf senescence. Transcriptional analysis revealed that WsPR-1 overexpression downregulated the GA 20-oxidase (GA20ox) gene involved in GA biosynthesis while upregulating GA 2-oxidase (GA2ox), a GA catabolic enzyme. Moreover, transcript levels of FRUITFULL (FUL) and LEAFY (NFL2) flowering genes exhibited a decrease in WsPR-1 plants, which could explain the delayed flowering and reduced seed pod development in transgenic plants. Confocal microscopy confirmed increased lignin deposition in stem cross-sections of WsPR-1 transgenic plants, supported by gene expression analysis and lignin content quantification. Additionally, our findings also suggest the involvement of Knotted1-like homeobox (KNOX) gene in enhancing cytokinin levels. This study highlights PR-1's regulatory role in plant growth and development, with potential to boost crop yields and enhance resilience.
  • Thumbnail Image
    Item
    Evolutionary and expression dynamics of LRR-RLKs and functional establishment of KLAVIER homolog in shoot mediated regulation of AON in chickpea symbiosis
    (Elsevier B.V., 2021) Tiwari, Manish; Pandey, Vimal; Singh, Baljinder; Yadav, Manisha; Bhatia, Sabhyata
    Chickpea shoot exogenously treated with cytokinin showed stunted phenotype of root, shoot and significantly reduced nodule numbers. Genome-wide identification of LRR-RLKs in chickpea and Medicago resulted in 200 and 371 genes respectively. Gene duplication analysis revealed that LRR-RLKs family expanded through segmental duplications in chickpea and tandem duplications in Medicago. Expression profiling of LRR-RLKs revealed their involvement in cytokinin signaling and plant organ development. Overexpression of KLAVIER ortholog of chickpea, Ca_LRR-RLK147, in roots revealed its localization in the membrane but showed no effect on root nodulation despite increased cle peptide levels. Two findings (i) drastic effect on nodule number by exogenous cytokinin treatment to only shoot and restoration to normal nodulation by treatment to both root and shoot tissue and (ii) no effect on nodule number by overexpression of Ca_LRR-RLK147 establishes the fact that despite presence of cle peptides in root, the function of Ca_LRR-RLK147 was shoot mediated during AON.
  • Thumbnail Image
    Item
    Evolutionary and functional analysis of Two-Component System in chickpea reveals CaRR13, a TypeB RR, as positive regulator of symbiosis
    (John Wiley & Sons, 2021) Tiwari, Manish; Yadav, Manisha; Singh, Baljinder; Pandey, Vimal; Nawaz, Kashif; Bhatia, Sabhyata
    The critical role of cytokinin in early nodulation in legumes is well known. In our study, exogenous cytokinin application to roots of the important crop legume, chickpea (Cicer arietinum L.) led to the formation of pseudo nodules even in the absence of rhizobia. Hence a genome-wide analysis of the cytokinin signaling, Two-Component System (TCS) genes was conducted in chickpea, Medicago and Cajanus cajan. The integrated phylogenetic, evolutionary and expression analysis of the TCS genes was carried out which revealed that Histidine Kinases (HKs) were highly conserved, whereas, there was diversification leading to neofunctionalization at the level of Response Regulators (RRs) especially the TypeB RRs. Further, the functional role of the CaHKs in nodulation was established by complementation of the sln1Δ mutant of yeast and cre1 mutants of (Medicago) which led to restoration of the nodule deficient phenotype. Additionally, the highest expressing TypeB RR of chickpea, CaRR13 was functionally characterized. Its localization in the nucleus and its Y1H assay-based interaction with the promoter of the early nodulation gene CaNSP2 indicated its role as a transcription factor regulating early nodulation. Overexpression, RNAi lines and complementation of cre1 mutants with CaRR13 revealed its critical involvement as an important signaling molecule regulating early events of nodule organogenesis in chickpea.
  • Thumbnail Image
    Item
    Expression profiling of miRNAs indicates crosstalk between phytohormonal response and rhizobial infection in chickpea
    (Springer Nature Publishing AG, 2020) Tiwari, Manish; Bhatia, Sabhyata
    Legumes develop root nodules in which bacteria fix nitrogen for plants. The phytohormones auxin and cytokinin regulate nodule organogenesis by recruiting various genes to effect symbiosis. Moreover, these genes are regulated by the action of microRNAs also. To understand the complex regulatory network involving miRNAs in response to phytohormones and rhizobial interactions in chickpea roots, a miRNA expression profiling was performed. Indole acetic acid and 6-benzylaminopurine at concentrations of 0.1, 1 and 10 lM were used for auxin and cytokinin exogenous treatment and Mesorhizobium ciceri to study rhizobial interaction with chickpea root. Expression profiling of a set of 11 miRNAs was performed. Further, the targets of the candidate miRNAs were identified, followed by functional annotation. This analysis revealed that cat-miR160, cat-miR164, cat-miR396 and cat-miR398 were responsive to auxin and cytokinin. cat-miR319 was found to be only auxin responsive and is known to regulate auxin signalling by targeting TEOSINTE BRANCHED/ CYCLOIDEA/PCF (TCP) which interacts with auxin inducible genes. Further, cytokinin elicited a response at very low concentration of 0.1 lM, and most of the miRNAs investigated were responsive to cytokinin. Interactome analysis revealed that cat-miR164 and cat-miR168 work in conjunction to regulate auxin signalling. Interestingly, cat-miR169 and cat-miR482 were low expressing during auxin treatment and M. ciceri infection but their expression spiked during cytokinin treatment, indicating a cytokinin mediated mode of action. The miRNA expression profiling in response to phytohormones and rhizobia and the reported function of their target genes suggested a crosstalk among the phytohormonal responses during chickpea nodulation.