Publications of NIPGR Scientists
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Item The Mediator complex subunit, OsMED26_2, modulates plant growth, seed set and seed traits related to starch quality in rice(Elsevier B.V., 2026) Prusty, Ankita; Malik, Naveen; Ranjan, Rajeev; Agarwal, Pinky; Parida, Swarup K.; Kapoor, Sanjay; Tyagi, Akhilesh K.The Mediator (MED) complex is a multi-subunit structure crucial for RNA polymerase II-dependent transcription in eukaryotes. In this study, we investigated the function of a seed-preferential subunit of the rice Mediator complex, namely, OsMED26_2, for the first time. Knockdown of OsMED26_2 in rice reduced plant height and altered panicle morphology with shorter panicles, lesser branching, and fewer seeds per panicle. OsMED26_2 knockdown also led to shorter grains with shorter length and chalky endosperm. A significantly higher percentage of grains with chalkiness (PGWC) and degree of chalky endosperm (DCE) was observed in OsMED26_2 knockdown lines. OsMED26_2-knockdown seeds contained lower starch levels and altered proportions of amylose and amylopectin. Scanning electron microscopy further showed that these changes caused irregular, round, and loosely packed starch granules in the endosperm, contributing to the chalky phenotype. Decreased amylose content and increased grain chalkiness were corroborated by the downregulation of the Waxy (Wx) gene, which is involved in amylose synthesis, and altered expression of AMY3A, CHALK5, FLO4, GPA3, and SUSY3 genes, which regulate grain chalkiness. Our findings demonstrate that OsMED26_2 is critical in regulating panicle architecture, impacting yield, and modulating starch level and composition to control grain chalkiness and thereby suggesting its functional significance especially in manipulating yield attributing grain cooking quality traits of rice.Item Rice Mitogen-Activated Protein Kinase regulates serotonin accumulation and interacts with cell cycle regulators under prolonged UV-B exposure(Elsevier B.V., 2023) Banerjee, Gopal; Singh, Dhanraj; Pandey, Chandana; Jonwal, Sarvesh; Basu, Udita; Parida, Swarup K.; Pandey, Ashutosh; Sinha, Alok KrishnaStress conditions such as UV-B exposure activates MAPKs in Arabidopsis and rice. UV-B radiation is hazardous to plant as it causes photosystem disruption, DNA damage and ROS generation. Here we report its effect on biological pathways by studying the global changes in transcript profile in rice seedling exposed to UV-B radiation for 1 h and 16 h. Short UV-B exposure (1 h) led to moderate changes, while a drastic change in transcript landscape was observed after long term UV-B exposure (16 h) in rice seedlings. Prolonged UV-B exposure negatively impacts the expression of cell cycle regulating genes and several other metabolic pathways in developing seedlings. MAP kinase signaling cascade gets activated upon UV-B exposure similar to reports in Arabidopsis indicating conservation of its function in both dicot and monocot. Expression analysis in inducible overexpression transgenic lines of MPK3 and MPK6 shows higher transcript abundance of phytoalexin biosynthesis gene like Oryzalexin D synthase and Momilactone A synthase, along with serotonin biosynthesis genes. An accumulation of serotonin was observed upon UV-B exposure and its abundance positively correlates with the MPK3 and MPK6 transcript level in the respective over-expression lines. Interestingly, multiple cell cycle inhibitor proteins including WEE1 and SMR1 interact with MPK3 and MPK6 thus, implying a major role of this pathway in cell cycle regulation under stress condition. Overall overexpression of MPK3 and MPK6 found to be detrimental for rice as overexpression lines shows higher cell death and compromised tolerance to UV-B.Item Cytological, transcriptome and miRNome temporal landscapes decode enhancement of rice grain size(BioMed Central Ltd, 2023) Mahto, Arunima; Yadav, Antima; Aswathi, P. V.; Parida, Swarup K.; Tyagi, Akhilesh K.; Agarwal, PinkyBackground Rice grain size (GS) is an essential agronomic trait. Though several genes and miRNA modules influencing GS are known and seed development transcriptomes analyzed, a comprehensive compendium connecting all possible players is lacking. This study utilizes two contrasting GS indica rice genotypes (small-grained SN and large-grained LGR). Rice seed development involves five stages (S1–S5). Comparative transcriptome and miRNome atlases, substantiated with morphological and cytological studies, from S1–S5 stages and flag leaf have been analyzed to identify GS proponents. Results Histology shows prolonged endosperm development and cell enlargement in LGR. Stand-alone and comparative RNAseq analyses manifest S3 (5–10 days after pollination) stage as crucial for GS enhancement, coherently with cell cycle, endoreduplication, and programmed cell death participating genes. Seed storage protein and carbohydrate accumulation, cytologically and by RNAseq, is shown to be delayed in LGR. Fourteen transcription factor families influence GS. Pathway genes for four phytohormones display opposite patterns of higher expression. A total of 186 genes generated from the transcriptome analyses are located within GS trait-related QTLs deciphered by a cross between SN and LGR. Fourteen miRNA families express specifically in SN or LGR seeds. Eight miRNA-target modules display contrasting expressions amongst SN and LGR, while 26 (SN) and 43 (LGR) modules are differentially expressed in all stages. Conclusions Integration of all analyses concludes in a “Domino effect” model for GS regulation highlighting chronology and fruition of each event. This study delineates the essence of GS regulation, providing scope for future exploits. The rice grain development database (RGDD) ( www.nipgr.ac.in/RGDD/index.php; https://doi.org/10.5281/zenodo.7762870) has been developed for easy access of data generated in this paper.Item Genome-wide analysis of polymorphisms identified domestication-associated long low diversity region carrying important rice grain size/weight QTL(John Wiley & Sons, 2020) Kumar, Angad; Daware, Anurag; Kumar, Arvind; Kumar, Vinay; Krishnan S, Gopala; Mondal, Subhasish; Patra, Bhaskar Chandra; Singh, Ashok. K.; Tyagi, Akhilesh K.; Parida, Swarup K.; Thakur, Jitendra K.Rice grain size and weight are major determinants of grain quality and yield and so have been under rigorous selection since domestication. However, genetic basis for contrasting grain size/weight trait among Indian germplasms and their association with domestication‐driven evolution is not well understood. In this study, two long (LGG) and two short grain (SGG) genotypes were resequenced. LGG (LGR and PB 1121) differentiated from SGG (Sonasal and Bindli) by 504,439 SNPs and 78,166 InDels. The LRK gene cluster was different and a truncation mutation in the LRK8 kinase domain was associated with LGG. Phylogeny with 3000 diverse rice accessions revealed that the four sequenced genotypes belonged to japonica group and were at the edge of the clades indicating them to be the potential source of genetic diversity available in Indian rice germplasm. Six SNPs were significantly associated with grain size/weight and top four of them could be validated in mapping population, suggesting this study as a valuable resource for high‐throughput genotyping. A contiguous ~ 6 Mb long low diversity region (LDR) carrying a major grain weight QTL (harbouring OsTOR gene) was identified on chromosome 5. This LDR was identified as an evolutionary important site with significant positive selection and multiple selection sweeps, and showed association with many domestication‐related traits including grain size/weight. The aus population retained more allelic variations in the LDR than japonica and indica populations, suggesting it to be one of the divergence loci. All the data and analyses can be accessed from RiceSzWtBase database.Item Transcription factor OsNF-YB9 regulates reproductive growth and development in rice(Springer Nature Publishing AG, 2019) Das, Sweta; Parida, Swarup K.; Agarwal, Pinky; Tyagi, Akhilesh K.Nuclear Factor-Y (NF-Y) family of transcription factors takes part in many aspects of growth and development in eukaryotes. They have been classifed into three subunit classes, namely, NF-YA, NF-YB and NF-YC. In plants, this transcription factor family is much diverged and takes part in several developmental processes and stress. We investigated NF-Y subunit genes of rice (Oryza sativa) and found OsNF-YB9 as the closest homologue of LEAFY COTYLEDON1. OsNF-YB9 delayed the heading date when ectopically expressed in rice. Expression of several heading date regulating genes such as Hd1, Ehd1, Hd3a and RFT1 were altered. OsNF-YB9 overexpression also resulted in morphological defects in the reproductive organs and led to pseudovivipary. OsNF-YB9 interacted with MADS1, a key regulator of foral development. This NF-Y subunit acted upstream to several transcription factors as well as signalling proteins involved in brassinosteroid and gibberellic acid metabolism and cell cycle. OsNF-YB9 and OsNF-YC12 interacted in planta and the latter also delayed heading in rice upon overexpression suggesting its involvement in a similar pathway. Our data provide new insights into the rice heading date pathway integrating these OsNF-Y subunit members to the network. These features can be exploited to improve vegetative growth and yield of rice plants in future.Item Rice improvement through genome-based functional analysis and molecular breeding in India(Springer, 2016) Agarwal, Pinky; Parida, Swarup K.; Raghuvanshi, Saurabh; Kapoor, Sanjay; Khurana, Paramjit; Khurana, Jitendra P.; Tyagi, Akhilesh K.Rice is one of the main pillars of food security in India. Its improvement for higher yield in sustainable agriculture system is also vital to provide energy and nutritional needs of growing world population, expected to reach more than 9 billion by 2050. The high quality genome sequence of rice has provided a rich resource to mine information about diversity of genes and alleles which can contribute to improvement of useful agronomic traits. Defining the function of each gene and regulatory element of rice remains a challenge for the rice community in the coming years. Subsequent to participation in IRGSP, India has continued to contribute in the areas of diversity analysis, transcriptomics, functional genomics, marker development, QTL mapping and molecular breeding, through national and multi-national research programs. These efforts have helped generate resources for rice improvement, some of which have already been deployed to mitigate loss due to environmental stress and pathogens. With renewed efforts, Indian researchers are making new strides, along with the international scientific community, in both basic research and realization of its translational impact.Item Sequence and expression analyses of KIX domain proteins suggest their importance in seed development and determination of seed size in rice, and genome stability in Arabidopsis(Springer, 2013) Thakur, Jitendra K.; Agarwal, Pinky; Parida, Swarup K.; Bajaj, Deepak; Pasrija, RichaThe KIX domain, which mediates protein-protein interactions, was first discovered as a motif in the large multidomain transcriptional activator histone acetyltransferase p300/CBP. Later, the domain was also found in Mediator subunit MED15, where it interacts with many transcription factors. In both proteins, the KIX domain is a target of activation domains of diverse transcription activators. It was found to be an essential component of several specific gene-activation pathways in fungi and metazoans. Not much is known about KIX domain proteins in plants. This study aims to characterize all the KIX domain proteins encoded by the genomes of Arabidopsis and rice. All identified KIX domain proteins are presented, together with their chromosomal locations, phylogenetic analysis, expression and SNP analyses. KIX domains were found not only in p300/CBP- and MED15-like plant proteins, but also in F-box proteins in rice and DNA helicase in Arabidopsis, suggesting roles of KIX domains in ubiquitin-mediated proteasomal degradation and genome stability. Expression analysis revealed overlapping expression of OsKIX_3, OsKIX_5 and OsKIX_7 in different stages of rice seeds development. Moreover, an association analysis of 136 in silico mined SNP loci in 23 different rice genotypes with grain-length information identified three non-synonymous SNP loci in these three rice genes showing strong association with long- and short-grain differentiation. Interestingly, these SNPs were located within KIX domain encoding sequences. Overall, this study lays a foundation for functional analysis of KIX domain proteins in plants.