Institutional Publications
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Item Temperature regulation of cell cycle and growth dynamics in Arabidopsis(Portland Press, 2026) Sundaravadivelu, Vasundara; Raipuria, Ritesh Kumar; Ranjan, AashishThe plant cell cycle is a highly coordinated and regulated process that integrates endogenous and environmental signals to control cell division, meristem maintenance, and cell fate specification for growth and development. Temperature is a critical environmental signal that regulates the cell cycle to manifest developmental plasticity in Arabidopsis roots and shoots. Arabidopsis plants exhibit either adaptive growth responses or arrested growth, depending on the temperature regime. The temperature-mediated growth dynamics in Arabidopsis involve altered cell-cycle regulation. While plant developmental and physiological responses to temperature have been extensively studied, the integration of temperature signalling cues with cell-cycle dynamics to regulate growth adaptation remains poorly understood. The present review not only compiles existing information on temperature-mediated regulation of cell-cycle dynamics but also provides a perspective on multidisciplinary approaches to investigate cell-cycle dynamics at spatiotemporal resolution in Arabidopsis adaptive growth responses.Item Organized peripheral vascular strand development in nodules is controlled by a bHLH/HLH heterodimer(John Wiley & Sons, 2026) Srivastava, Deevita; Bhadu, Vikash; Sahoo, Rudra Narayan; Ghosh, Asim Kumar; Upadhyay, Priya; Bhardwaj, Akanksha; Udvardi, Michael K; Ranjan, Aashish; Sinharoy, SenjutiThe Leguminosae family can develop root nodules with symmetrical peripheral vascular-strands (PVSs). Medicago truncatula forms indeterminate nodules with PVSs. The PVSs elongate directly from the root toward the nodule apex, maintaining a symmetrical organization and facilitating the formation of the cylindrical nodule structure. By combining genetic, biochemical, and genomic tools, we have shown that two basic Helix-Loop-Helix groups of transcription factors, MtbHLH1 (renamed Nodule Vascular bundle Development 1 (NVD1)) and NVD2, control the development of symmetrical PVSs in M. truncatula. In nvd1 nodules, PVSs drift toward the infection zone, generating aberrantly shaped nodules. NVD1 activates its expression along with NVD2, a transcriptional regulator. NVD1 functions downstream of auxin signaling. Transcriptome sequencing of nvd1 and nvd2 nodules, combined with visualization of auxin and cytokinin (CK) signal outputs, revealed disrupted auxin and CK signaling in nvd nodules. Furthermore, ectopic expression of the auxin biosynthetic enzyme (MtYUCCA8) under pMtNVD1 and pMtNVD2 resulted in defective PVSs. Mutant nvd2 nodules display asymmetric PVSs. NVD2 regulates the transcriptional activity of NVD1 by forming heterodimers with it. The formation of symmetrical PVSs depends on the balanced presence of NVD1 and NVD2. Our findings highlight the pivotal role of the NVD1-NVD2 interaction in shaping the development of symmetrical PVSs.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, AashishTillering 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.Item RSD-mediated suppression of NIN and NLP2 transcription is crucial for symbiotic nitrogen fixation(John Wiley & Sons, 2026) Bhardwaj, Akanksha; Gupta, Megha; Bhattacharjee, Oindrila; Raul, Bikash; Ghosh, Asim Kumar; Nagalla, L. V. Sairam; Yadav, Prashant; Bandyopadhyay, Kaustav; Ranjan, Aashish; Sinharoy, SenjutiIndeterminate nodules establish a developmental gradient along their longitudinal axis, separating cell differentiation from symbiotic nitrogen fixation (SNF). The apex contains differentiating cells, while the differentiated leghemoglobin-rich cells of the nitrogen-fixation zone shield the rhizobial nitrogenase complex from oxygen to facilitate SNF. By combining biochemical, genetic, and genomic approaches, we demonstrate the pivotal role of the Regulator of Symbiosome Differentiation (RSD), a transcriptional repressor, in the transition from symbiosome development to SNF. Interacting Protein of DMI3 (IPD3) activates RSD expression in the invasion zone (ZII) and interzone (IZ). RSD interacts with Nodule Inception (NIN), and NIN-like protein 2 (NLP2) through a novel protein-protein interaction domain. RSD determines cell fate in ZII and the IZ by suppressing several targets of NIN and NLP2, including Leghemoglobins, Nodule-specific Cysteine-Rich genes, and Symbiotic Cysteine-rich Receptor-like Kinase. Our findings underscore the critical role of RSD-mediated suppression of transcription in facilitating the transition from bacteroid differentiation to SNF.Item Optimizing photosynthesis by targeting light signaling transcriptional networks(Oxford University Press, 2026) Sanyal, Rajarshi; Ranjan, AashishLight serves as a crucial environmental signal for plants besides providing energy for photosynthesis. Photomorphogenesis, light-induced plant developmental responses, involves photoreceptors perceiving light signals to initiate signaling cascades with downstream transcriptional networks. Moreover, light is also absorbed by photopigments to drive photosynthetic light reactions, providing energy for growth and metabolism. As light serves as a primary cue for both photomorphogenesis and photosynthesis, a crosstalk between the two processes is anticipated. While transcriptional regulation of photomorphogenesis is investigated in detail, our understanding of the transcriptional control of photosynthesis remains limited. Recent studies have shown the involvement of photoreceptors and key light-signaling transcription factors, such as PHYTOCHROME-INTERACTING FACTORs (PIFs) and ELONGATED HYPOCOTYL 5 (HY5), in the regulation of photosynthesis. This review not only highlights the transcriptional regulation of photosynthesis but also provides a broader perspective on the involvement of key transcription factors of photomorphogenesis in the regulation of photosynthesis. The review further discusses strategies to investigate and manipulate the light signaling transcriptional regulatory networks for optimizing photosynthetic efficiency.Item Induced post-invasive defenses in the nonhost plant Parthenium hysterophorus L. prevent root cortical colonization by Macrophomina phaseolina and impart resistance to dry root rot(Elsevier B.V., 2025) Mirchandani, Rishabh; Kandpal, Manu; Ranjan, Aashish; Sinharoy, Senjuti; Senthil-Kumar, MuthappaDry root rot (DRR) of chickpea is caused by the broad-range necrotrophic fungus Macrophomina phaseolina. Chickpea germplasm does not provide durable resistance to DRR, which is particularly devastating under drought. Even moderately resistant chickpea varieties become susceptible under combined stress. We hypothesized that nonhost resistance (NHR) is durable even under combined stress. Using the blotter paper assay and stereomicroscopic observations, we identified the asterid weed Parthenium hysterophorus as a potential nonhost of M. phaseolina among 82 potential nonhosts. Epidermal necrotic lesions were prevented in P. hysterophorus. In planta fungal load was 0.195 and 0.007 ng/ng total DNA in chickpea and P. hysterophorus, respectively. M. phaseolina could not colonize the P. hysterophorus root while up to 6 cortical cell layers were colonized in chickpea. Further, NHR was durable under combined stress. Dual RNA sequencing revealed that M. phaseolina actively attempted to infect the nonhost and activated specific genes in the xenobiotics degradation pathway. P. hysterophorus also showed an active defense response with1958 and 2294 differentially expressed genes at 2 and 4 DAI, respectively, with 363 upregulated at both time points. Differential expression of cell wall synthesis, phytohormone signaling, and other defense response pathways likely contributes to NHR. Few genes in the phenylpropanoid biosynthesis pathways in P. hysterophorus were also upregulated, possibly because these metabolites are linked to the distinct changes in the fungus during nonhost infection. We therefore conclude that P. hysterophorus exhibits post-invasive NHR to M. phaseolina and that general defense, phytohormone signaling and secondary metabolic pathways contribute to NHR.Item Integration of metabolite and transcriptome profiles of cultivated and wild rice to unveil gene regulatory networks and key genes determining rice source and sink strength(Springer Nature Publishing AG, 2025) Singh, Anuradha; Mathan, Jyotirmaya; Dwivedi, Aditi; Rani, Ruchi; Ranjan, AashishTargeting source and sink strength for crop yield increase requires a comprehensive genetic and metabolic understanding of desirable source and sink features. We performed comprehensive metabolite and transcriptomic comparisons of the photosynthetic flag leaves and milky-stage developing grains of two cultivated rice varieties (Oryza sativa L. ssp. Indica cv. IR64 and Oryza sativa L. ssp. Japonica cv. Nipponbare) and two wild rice accessions (Oryza rufipogon and Oryza australiensis). The selected wild rice accessions had stronger source strength as evidenced by a higher photosynthesis rate and more abundance of primary metabolites in the photosynthetic leaves than the cultivated varieties. In contrast, cultivated varieties had efficient sink as grains were bigger and accumulated more sugars, amino acids, and fatty acids than the selected wild rice. Transcriptomic analyses identified 9,309 genes for efficient source in wild rice, enriched for biological pathways related to photosynthesis, carbohydrate metabolism, and sucrose transport. 7,062 genes, enriched for starch biosynthesis and lipid metabolism, were associated with the efficient sink strength in the cultivated varieties. Gene co-expression networks showed 267 hub genes for source strength in wild rice that included important genes for photosynthetic reactions and sucrose metabolism. 196 hub genes for sink strength in cultivated rice included genes involved in sucrose, amino acid, and fatty acid metabolism. Gene co-expression modules further identified the candidate transcription regulators, such as zinc finger proteins and NAC for source strength and MYB55/80 and MADS64 for sink strength. Moreover, our analyses suggested a complex interplay of phytohormones regulating rice source and sink strength.Item Revisiting development and physiology of wild rice relatives for crop improvement and climate resilience(Springer Nature Publishing AG, 2025) Mathan, Jyotirmaya; Dwivedi, Aditi; Ranjan, AashishIncreasing rice yield and productivity under changing climatic conditions is imperative for sustainable food security, given rice is a major staple crop around the world. Natural variation in crop plants, including wild relatives, offers remarkable genetic variability to explore the desirable developmental and physiologic traits for crop improvement. Wild relatives of rice, with distinct developmental and physiologic features compared to cultivated varieties, are the potential genetic and genomic resource for rice yield increases under changing climate. A thorough genetic basis of rice developmental and architectural changes during domestication is now established with the identification and characterization of domestication genes. Photosynthetically efficient wild rice accessions, with desirable developmental, physiologic, and metabolic traits, have been identified in recent years that could be instrumental for rice improvement. While several abiotic and biotic stress-tolerant wild relatives of rice along with the associated genetic loci have been identified over the years, a comprehensive insight into the desirable developmental and physiologic attributes of the wild rice is limited. Moreover, the usage of wild rice is not streamlined in rice-improvement programs due to genetic and genomic constraints. In this review, we summarize the desirable developmental and physiologic features of wild rice species that can be exploited for combining yield increases with climate resilience in rice-improvement programs.Item In-silico prediction of coat protein structure of Indian citrus ringspot virus and their interactions with the Argonaut2/DCL4 proteins(Springer Nature Publishing AG, 2025) Angira, Aniket; Yadav, Siddharth; Mathur, Puniti; Baranwal, V. K.; Ranjan, Aashish; Choudhary, NandlalThe RNA silencing mechanism is a crucial regulatory system in plants, particularly in antiviral defense. However, most of the plant viruses encode a specifc protein called RNA silencing suppressor protein that suppress the RNA silencing mechanism of host. This study employs the bioinformatics tools, including SWISS homology model and I-TASSER, to predict the coat protein (CP) tertiary structure of Indian citrus ringspot virus (ICRSV). Then, fve protein–protein docking servers (GRAMM, pyDockWEB, HawkDock, ZDOCK and ClusPro) were utilized to investigate interactions of CP of ICRSV with Argonaut2/Dicer-Like (DCL4) protein 4 of RNA silencing pathway of host. In blind docking experiments, the CP consistently engaged in docking interactions with DCL4, while with AGO2, it interacted near the PIWI and MID domains. The AGO2-CP cluster demonstrated 4 salt bridges, 30 hydrogen bonds, and 328 non-bonded contacts, with interface areas spanning 2529 in AGO2 and 2424 in CP, involving 50 and 51 interface residues, respectively. Similarly, the DCL4-CP cluster showed 5 hydrogen bonds and 122 non-bonded contacts, with interface areas spanning 965 in DCL4 and 987 in CP, involving 16 and 19 interface residues, respectively. The established phenomenon of CP interaction with AGO2/DCL4, may resulting in the inhibition of the RNA silencing mechanism and shedding light on the suppression mechanisms of host defense responses.Item Identification of an RNA silencing suppressor encoded by an Indian citrus ringspot virus(Springer Nature Publishing AG, 2025) Angira, Aniket; Baranwal, V. K.; Ranjan, Aashish; Choudhary, NandlalPlant viruses encode RNA silencing suppressor (RSS) proteins to counter the induced antiviral defense, an RNAi silencing mechanism of the host. Indian citrus ringspot virus (ICRSV) causes the ringspot disease, which leads to signifcant yield loss of kinnow orange. The ICRSV genome contains six open reading frames (ORFs), however, the ORF encoding the potential RSS is not yet known. In this study, we have attempted to identify the RSS protein of ICRSV. To this end, ORF 2,3,4,5 and 6 were cloned into pCAMBIA1302 (35s-GFP) vector, followed by transformation of Agrobacterium tumefaciens and agro-infltration into leaves of Nicotiana benthamiana 16c line. Only the leaves infltrated with 35s-GFP/ORF5 showed a GFP fuorescence signal similar to 35s-GFP/P19, a well-studied positive RSS. Usually, the induced host RNAi silencing is supposed to cleave the expressed GFP-RNA. However, it is suspected that ORF5-encoded protein was able to suppress the host silencing mechanism, leading to the retention of the GFP fuorescence signal. This fnding was further supported by beta-glucuronidase (GUS) histochemical assays by infltrating the construct expressing ORF5-GUS under 35s promoter in the leaves of N. benthamiana. Leaves infltrated with 35s-GUS/ORF5 formed diX-indigo precipitate similar to leaves infltrated with, indicating the RSS activity of ICRSV. Later, semi-quantitative PCR and quantitative reverse transcription PCR (qRT-PCR) assays showed a higher expression of GFP and GUS in ORF5 agro-infltrated leaves. Together, these results suggest that ORF5 encoded protein has the potential RSS function of ICRSV which successfully suppresses host RNAi silencing mechanism.