Institutional Publications
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Item Stripping off the rice panicle: induced genetic variation awakens the sheathed spikelet for a better yield(Oxford University Press, 2024) Mohanty, Jitendra K.; Parida, Swarup K.The rice panicle is the reproductive structure that contains the seeds, so a productive spikelet in a panicle contributes to increased yield. A sheathed panicle covers a signifcant portion of spikelets with the fag leaf and impairs effective pollination which subsequently compromises the yield. Through induced mutagenesis and integrated molecular breeding strategies, Ballichatla et al. (2024) uncovered the intricate regulation of complete panicle exsertion (CPE) in rice. This study also delineates a set of high-confdence novel genomic loci and superior gene alleles which have a substantial translational signifcance in rice crop improvement towards future food security.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 SUPER STARCHY1/ONAC025 participates in rice grain filling(American Society of Plant Biologists, 2020) Mathew, Iny Elizebeth; Priyadarshini, Richa; Mahto, Arunima; Jaiswal, Priya; Parida, Swarup K.; Agarwal, PinkyNAC transcription factors (TFs) are known for their role in development and stress. This article attempts to functionally validate the role of rice SS1/ ONAC025 (LOC_ Os11g31330) during seed development. The gene is seed-specific and its promoter directs reporter expression in the developing endosperm and embryo in rice transgenic plants. Furthermore, rice transgenic plants ectopically expressing SS1/ ONAC025 have a plantlet lethal phenotype with hampered vegetative growth, but increased tillers and an altered shoot apical meristem structure. The vegetative cells of these plantlets are filled with distinct starch granules. RNAseq analysis of two independent plantlets reveals the differential expression of reproductive and photosynthetic genes. A comparison with seed development transcriptome indicates differential regulation of many seed-related genes by SS1/ ONAC025. Genes involved in starch biosynthesis, especially amylopectin and those encoding seed storage proteins, and regulating seed size are also differentially expressed. In conjunction, SS1/ ONAC025 shows highest expression in japonica rice. As a TF, SS1/ ONAC025 is a transcriptional repressor localized to endoplasmic reticulum and nucleus. The article shows that SS1/ ONAC025 is a seed-specific gene promoting grain filling in rice, and negatively affecting vegetative growth.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 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 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.