Publications of NIPGR Scientists

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Start date: 2020Subject: search.filters.subject.seed development

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    Decoding rice seed storage proteins: From gene identification to structural prediction
    (Oxford University Press, 2026) Yadav, Antima; Jaiswal, Priya; Mathew, Iny Elizebeth; Panwar, Akanksha; Agarwal, Pinky
    Background and Aims: Rice seed storage proteins (SSPs) are major determinants of grain nutritional quality, serving as primary sources of dietary protein, energy, and essential nutrients. However, limited understanding of their diversity, evolution, and regulation constrains efforts to improve grain quality. This study aimed to perform a comprehensive genome-wide characterization of SSPs in rice. Methods: A combined homology- and domain-based approach was employed to identify SSP-encoding genes in the rice genome. These proteins were further analysed through phylogenetic reconstruction, domain and motif characterization, promoter cis-element analysis, expression profiling across seed developmental stages, and three-dimensional structural modelling. Key Results: A total of 65 SSP genes were identified, including 19 previously uncharacterized members. Phylogenetic and domain analyses revealed evolutionary relationships between albumins and prolamins, and between globulins and glutelins. Tandem clustering of albumins, glutelins, and prolamins suggested gene duplication as a major driver of SSP family expansion. Expression profiling indicated that albumins, globulins, and glutelins were transcriptionally active from the S2 stage, whereas prolamins were predominantly expressed from the S3 stage onwards. Promoter analysis identified several seed-specific cis-regulatory elements, including CAATBOX1, EBOXBNNAPA, and DOFCOREZM. Structural modelling showed that albumins and prolamins are primarily composed of α-helices, while globulins and glutelins are enriched in β-strands and coils. Conclusions: This integrative analysis provides comprehensive insights into the classification, evolution, regulatory mechanisms, and structural features of rice SSPs. The findings establish a valuable resource for future functional studies and offer a foundation for strategies aimed at improving grain nutritional quality.
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    Silencing of an ubiquitin ligase increases grain width and weight in indica rice
    (Frontiers Media S.A., 2021) Verma, Ankit; Prakash, Geeta; Ranjan, Rajeev; Tyagi, Akhilesh K.; Agarwal, Pinky
    Many quantitative trait loci (QTLs) have been identified by molecular genetic studies which control grain size by regulating grain width, length, and/or thickness. Grain width 2 (GW2) is one such QTL that codes for a RING-type E3 ubiquitin ligase and increases grain size by regulating grain width through ubiquitin-mediated degradation of unknown substrates. A natural variation (single-nucleotide polymorphism at the 346th position) in the functional domain-coding region of OsGW2 in japonica rice genotypes has been shown to cause an increase in grain width/weight in rice. However, this variation is absent in indica rice genotypes. In this study, we report that reduced expression of OsGW2 can alter grain size, even though natural sequence variation is not responsible for increased grain size in indica rice genotypes. OsGW2 shows high expression in seed development stages and the protein localizes to the nucleus and cytoplasm. Downregulation of OsGW2 by RNAi technology results in wider and heavier grains. Microscopic observation of grain morphology suggests that OsGW2 determines grain size by influencing both cell expansion and cell proliferation in spikelet hull. Using transcriptome analysis, upregulated genes related to grain size regulation have been identified among 1,426 differentially expressed genes in an OsGW2_RNAi transgenic line. These results reveal that OsGW2 is a negative regulator of grain size in indica rice and affects both cell number and cell size in spikelet hull.
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    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, Pinky
    NAC 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.