Institutional Publications
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Item Zinc finger transcriptional repressor ZOS5-09 regulates grain filling and development in rice(John Wiley & Sons, 2025) Jaiswal, Priya; Qasim, Falah; Mahto, Arunima; Vichitra, Ankur; Das, Upasana; Tyagi, Akhilesh K.; Agarwal, PinkyGrain size is one of the key determinants of grain yield. Our study focuses on a novel seed-preferential C2H2 zinc finger transcription factor, ZOS5-09 (LOC_Os05g38600) that plays an important role in regulating rice grain traits. Rice plants with the ZOS5-09 promoter::GUS construct showed high expression of ZOS5-09 in rice endosperm. In planta reporter effector assays and localization studies showed that ZOS5-09 is a nuclear-localized transcriptional repressor. It has two C2H2 zinc finger domains and a C-terminal NoRS (nucleolar retention signal). Ectopic and seed-preferential overexpression of ZOS5-09 resulted in lethality. Seed-preferential overexpression without NoRS was detrimental to grain filling. Rice plants with knock-down or CRISPR-based knock-out of ZOS5-09 displayed reduced grain length and weight but increased grain width. Grain size change was due to lower cell proliferation and increased cell size in the transverse direction because of downregulation of cell cycle-related genes and increased expression of expansins. Decreased expression of ZOS5-09 also resulted in reduced total starch and protein content and higher endosperm chalkiness, thus negatively affecting grain quality. ZOS5-09 directly bound to a zinc finger–binding site and regulated a seed storage protein-encoding gene, GLU6. It acted as a repressor by promoting deacetylation upon interaction with a histone deacetylase. In summary, our results indicate that an optimum expression of ZOS5-09 is essential for proper rice grain development. Our study highlights the role of a transcriptional repressor in regulating rice grain traits and improves our understanding of the transcriptional regulatory networks affecting grain size.Item Emerging molecular strategies for improving rice drought tolerance(Bentham Science, 2021) Giri, Jitender; Parida, Swarup K.; Raghuvanshi, Saurabh; Tyagi, Akhilesh K.Rice occupies a pre-eminent position as a food crop in the world. Its production, however, entails up to 3000 liters of water per kilogram of grain produced. Such high demand makes rice prone to drought easily. Sustainable rice cultivation with limited water resources requires the deployment of a suitable strategy for better water use efficiency and improved drought tolerance. Several drought-related genes have been evaluated in rice for their mode of action in conferring drought tolerance. Manipulation of components of abscisic acid signal transduction, stomatal density, deposition of cuticular wax, and protein modification pathways are emerging as priority targets. Gene reprogramming by microRNAs is also being explored to achieve drought tolerance. Genetically dissected Quantitative Trait Loci (QTLs) and their constituent genes are being deployed to develop drought-tolerant rice varieties. Progressive research and challenges include a better understanding of crucial components of drought response and search for new targets and the deployment of improved varieties in the field.Item Mediator subunit OsMED14_1 plays an important role in rice development(John Wiley & Sons, 2020) Malik, Naveen; Ranjan, Rajeev; Parida, Swarup K.; Agarwal, Pinky; Tyagi, Akhilesh K.Mediator, a multi‐subunit coactivator complex, regulates transcription in eukaryotes and is involved in diverse processes in Arabidopsis through its different subunits. Here, we have explored developmental aspects of one of the rice Mediator subunit gene OsMED14_1. We analyzed its expression pattern through RNA in‐situ hybridization and pOsMED14_1:GUS transgenics which showed its expression in roots, leaves, anthers and seeds prominently at younger stages, indicating possible involvement of this subunit in multiple aspects of rice development. To understand developmental roles of OsMED14_1 in rice, we generated and studied RNAi based knockdown rice plants which showed multiple effects including less height, narrower leaves and culms with reduced vasculature, lesser lateral root branching, defective microspore development, reduced panicle branching and seed set, and smaller seeds. Histological analyses showed that slender organs were caused by reduction in both cell number and cell size in OsMED14_1 knockdown plants. Flow cytometric analyses and expression analyses of cell‐cycle related genes revealed that defective cell‐cycle progression led to these defects. Expression analyses of auxin related genes and IAA immuno‐localization study indicated altered auxin level in these knockdown plants. Reduction of lateral root branching in knockdown plants was corrected by exogenous IAA supplement. OsMED14_1 physically interacts with transcription factors YABBY5, TDR and MADS29, possibly regulating auxin homeostasis and ultimately leading to lateral organ/leaf, microspore and seed development.Item Analysis of rice proteins with DLN repressor Motif/S(MDPI AG, 2019) Singh, Purnima; Mathew, Iny Elizebeth; Verma, Ankit; Tyagi, Akhilesh K.; Agarwal, PinkyTranscriptional regulation includes both activation and repression of downstream genes. In plants, a well-established class of repressors are proteins with an ERF-associated amphiphilic repression/EAR domain. They contain either DLNxxP or LxLxL as the identifying hexapeptide motif. In rice (Oryza sativa), we have identified a total of 266 DLN repressor proteins, with the former motif and its modifications thereof comprising 227 transcription factors and 39 transcriptional regulators. Apart from DLNxxP motif conservation, DLNxP and DLNxxxP motifs with variable numbers/positions of proline and those without any proline conservation have been identified. Most of the DLN repressome proteins have a single DLN motif, with higher relative percentage in the C-terminal region. We have designed a simple yeast-based experiment wherein a DLN motif can successfully cause strong repression of downstream reporter genes, when fused to a transcriptional activator of rice or yeast. The DLN hexapeptide motif is essential for repression, and at least two “DLN” residues cause maximal repression. Comparatively, rice has more DLN repressor encoding genes than Arabidopsis, and DLNSPP motif from rice is 40% stronger than the known Arabidopsis SRDX motif. The study reports a straightforward assay to analyze repressor activity, along with the identification of a strong DLN repressor from rice.Item Regional association analysis of metaQTLs delineates candidate grain size genes in rice(Frontiers Media S.A., 2017) Daware, Anurag V.; Srivastava, Rishi; Singh, Ashok K.; Parida, Swarup K.; Tyagi, Akhilesh K.Molecular mapping studies which aim to identify genetic basis of diverse agronomic traits are vital for marker-assisted crop improvement. Numerous Quantitative Trait Loci (QTLs) mapped in rice span long genomic intervals with hundreds to thousands of genes, which limits their utilization for marker-assisted genetic enhancement of rice. Although potent, fine mapping of QTLs is challenging task as it requires screening of large number of segregants to identify suitable recombination events. Association mapping offers much higher resolution as compared to QTL mapping, but detects considerable number of spurious QTLs. Therefore, combined use of QTL and association mapping strategies can provide advantages associated with both these methods. In the current study, we utilized meta-analysis approach to identify metaQTLs associated with grain size/weight in diverse Indian indica and aromatic rice accessions. Subsequently, attempt has been made to narrow-down identified grain size/weight metaQTLs through individual SNP- as well as haplotype-based regional association analysis. The study identified six different metaQTL regions, three of which were successfully revalidated, and substantially scaled-down along with GS3 QTL interval (positive control) by regional association analysis. Consequently, two potential candidate genes within two reduced metaQTLs were identified based on their differential expression profiles in different tissues/stages of rice accessions during seed development. The developed strategy has broader practical utility for rapid delineation of candidate genes and natural alleles underlying QTLs associated with complex agronomic traits in rice as well as major crop plants enriched with useful genetic and genomic information.Item bHLH142 regulates various metabolic pathway-related genes to affect pollen development and anther dehiscence in rice(Nature Publishing Group, 2017) Ranjan, Rajeev; Khurana, Reema; Malik, Naveen; Badoni, Saurabh; Parida, Swarup K.; Kapoor, Sanjay; Tyagi, Akhilesh K.Apposite development of anther and its dehiscence are important for the reproductive success of the flowering plants. Recently, bHLH142, a bHLH transcription factor encoding gene of rice has been found to show anther-specific expression and mutant analyses suggest its functions in regulating tapetum differentiation and degeneration during anther development. However, our study on protein level expression and gain-of-function phenotype revealed novel aspects of its regulation and function during anther development. Temporally dissimilar pattern of bHLH142 transcript and polypeptide accumulation suggested regulation of its expression beyond transcriptional level. Overexpression of bHLH142 in transgenic rice resulted in indehiscent anthers and aborted pollen grains. Defects in septum and stomium rupture caused anther indehiscence while pollen abortion phenotype attributed to abnormal degeneration of the tapetum. Furthermore, RNA-Seq-based transcriptome analysis of tetrad and mature pollen stage anthers of wild type and bHLH142OEplants suggested that it might regulate carbohydrate and lipid metabolism, cell wall modification, reactive oxygen species (ROS) homeostasis and cell death-related genes during rice anther development. Thus, bHLH142 is an anther-specific gene whose expression is regulated at transcriptional and post-transcriptional/translational levels. It plays a role in pollen maturation and anther dehiscence by regulating expression of various metabolic pathways-related genes.Item Sub-functionalization in rice gene families with regulatory roles in abiotic stress responses(Taylor & Francis Group, 2017) Sharma, G.; Giri, Jitender; Tyagi, Akhilesh K.Plants have developed intricate mechanisms to overcome abiotic stresses. The process of signal perception and activation of signaling cascades involves a large number of factors and molecules belonging to diverse classes of gene families. In comparison to animals, plants harbor larger multigene families along with the occurrence of plant-specific ones. Gene families with abiotic-stress-responsive members were analyzed and categorized into classes such as transcription factors, signal transduction components, transporters, epigenetic regulators, and other regulatory components. The number of members, phylogeny, family expansion, domain composition, subcellular localization, and expression profiling during varied abiotic stresses have been summarized. Candidate genes from families, functionally characterized for abiotic stress responses, have been described. Based on our compilation, the expansion of abiotic-stress-responsive gene families in rice has occurred via segmental and tandem duplication events to accommodate sub-functionalization needed for regulating diverse abiotic stress responses at expression, localization, and functional levels. The information documented here can be further utilized as a primer for selecting candidate genes for improvement of rice yield under abiotic stresses.Item An efficient strategy combining SSR markers- and advanced QTL-seq-driven QTL mapping unravels candidate genes regulating grain weight in rice(Frontiers Media S.A., 2016) Daware, Anurag; Das, Sweta; Srivastava, Rishi; Badoni, Saurabh; Singh, Ashok K.; Agarwal, Pinky; Parida, Swarup K.; Tyagi, Akhilesh K.Development and use of genome-wide informative simple sequence repeat (SSR) markers and novel integrated genomic strategies are vital to drive genomics-assisted breeding applications and for efficient dissection of quantitative trait loci (QTLs) underlying complex traits in rice. The present study developed 6244 genome-wide informative SSR markers exhibiting in silico fragment length polymorphism based on repeat-unit variations among genomic sequences of 11 indica, japonica, aus, and wild rice accessions. These markers were mapped on diverse coding and non-coding sequence components of known cloned/candidate genes annotated from 12 chromosomes and revealed a much higher amplification (97%) and polymorphic potential (88%) along with wider genetic/functional diversity level (16–74% with a mean 53%) especially among accessions belonging to indica cultivar group, suggesting their utility in large-scale genomics-assisted breeding applications in rice. A high-density 3791 SSR markers-anchored genetic linkage map (IR 64 × Sonasal) spanning 2060 cM total map-length with an average inter-marker distance of 0.54 cM was generated. This reference genetic map identified six major genomic regions harboring robust QTLs (31% combined phenotypic variation explained with a 5.7–8.7 LOD) governing grain weight on six rice chromosomes. One strong grain weight major QTL region (OsqGW5.1) was narrowed-down by integrating traditional QTL mapping with high-resolution QTL region-specific integrated SSR and single nucleotide polymorphism markers-based QTL-seq analysis and differential expression profiling. This led us to delineate two natural allelic variants in two known cis-regulatory elements (RAV1AAT and CARGCW8GAT) of glycosyl hydrolase and serine carboxypeptidase genes exhibiting pronounced seed-specific differential regulation in low (Sonasal) and high (IR 64) grain weight mapping parental accessions. Our genome-wide SSR marker resource (polymorphic within/between diverse cultivar groups) and integrated genomic strategy can efficiently scan functionally relevant potential molecular tags (markers, candidate genes and alleles) regulating complex agronomic traits (grain weight) and expedite marker-assisted genetic enhancement in rice.Item Anthology of anther/pollen-specific promoters and transcription factors(Taylor & Francis, 2012) Khurana, Reema; Kapoor, Sanjay; Tyagi, Akhilesh K.Pollen, regarded as the gold dust carrying the male germ line of flowering plants, is generated in the male reproductive organ called stamen. During the last few years, molecular biology and genetics have been integrated to enhance our knowledge regarding the structural and functional aspects of anther and pollen development. The promoters of several anther-/pollen-specific genes have been characterized to help understand the development of anther that involves the expression of a large number of genes temporally as well as spatially. The cis-acting regulatory elements of promoters necessary for interaction with transcription factors and their activity have been delineated. Many transcription factor genes having distinct anther-specific expression pattern have been identified with the help of transcriptome studies in Oryza sativa as well as Arabidopsis thaliana. The nature of complex interactions between genes and regulatory hierarchy involving developmental signal cascades have been investigated to design a working model for anther development. The immediate challenge ahead is to isolate and functionally characterize missing links and terminal ends of regulatory components for enhancing our knowledge about the male gametophyte development. The information generated on this aspect would help design suitable strategies to develop traits such as male sterility in crop plants.Item Rice A20/AN1 zinc-finger containing stress-associated proteins (SAP1/11) and a receptor-like cytoplasmic kinase (OsRLCK253) interact via A20 zinc-finger and confer abiotic stress tolerance in transgenic Arabidopsis plants(Wiley-Blackwell, 2011) Giri, Jitender; Vij, Shubha; Dansana, Prasant K.; Tyagi, Akhilesh K.The inbuilt mechanisms of plant survival have been exploited for improving tolerance to abiotic stresses. Stress-associated proteins (SAPs), containing A20/AN1 zinc-finger domains, confer abiotic stress tolerance in different plants, however, their interacting partners and downstream targets remain to be identified. •In this study, we have investigated the subcellular interactions of rice SAPs and their interacting partner using yeast two-hybrid and fluorescence resonance energy transfer (FRET) approaches. Their efficacy in improving abiotic stress tolerance was analysed in transgenic Arabidopsis plants. Regulation of gene expression by genome-wide microarray in transgenics was used to identify downstream targets. •It was found that the A20 domain mediates the interaction of OsSAP1 with self, its close homolog OsSAP11 and a rice receptor-like cytoplasmic kinase, OsRLCK253. Such interactions between OsSAP1/11 and with OsRLCK253 occur at nuclear membrane, plasma membrane and in nucleus. Functionally, both OsSAP11 and OsRLCK253 could improve the water-deficit and salt stress tolerance in transgenic Arabidopsis plants via a signaling pathway affecting the expression of several common endogenous genes. •Components of a novel stress-responsive pathway have been identified. Their stress-inducible expression provided the protection against yield loss in transgenic plants, indicating the agronomic relevance of OsSAP11 and OsRLCK253 in conferring abiotic stress tolerance.