Biology subjects

Tyagi, A. K.

Publications and source records attributed to Tyagi, A. K..

7 recordsLinked to original sources

bioRxiv2024

A novel repressor-activator-competitor module comprising C2H2 zinc finger and NAC transcription factors regulates rice grain development

Grain size and quality are crucial agronomic traits. We have characterized a seed-preferential C2H2 zinc finger transcriptional repressor, ZOS1-15. Its overexpression, knock-down and knock-out plants indicated a negative control over grain size due to altered cell expansion. ZOS1-15 homodimerized and directly interacted with co-repressor TOPLESS and histone deacetylases to form a repression complex. ZOS1-15 also interacted with Mediator subunit MED14_1 and a seed-preferential transcriptional activator, ONAC024, with three alternatively spliced isoforms. The ectopic expression of ONAC024 negatively affected plant growth and development. Seed-preferential overexpression and knock-down plants showed ONAC024 as a positive regulator of grain length due to increased cell proliferation and expansion. CRES-T generated transgenic rice plants indicated a functional divergence amongst ONAC024 isoforms. Tandem interactions were observed between ONAC024-ONAC023-ONAC026-ONAC020. ZOS1-15 and ONAC024 functioned antagonistically to regulate grain amylose and SSP accumulation while ONAC023 affected only amylose. ZOS1-15 and ONAC024 directly regulated the expression of two SSP encoding genes. Binding of ONAC024 was competed by ONAC025-MADS29 complex. The seed-preferential overexpression of SS1/ ONAC025 resulted in decreased grain size and amylose content, but higher yield. This study proposes a repressor-activator-competitor module, wherein ZOS1-15, ONAC024, ONAC023, ONAC025 along with their interactors synergistically and antagonistically regulate multiple aspects of rice grain development.

plant biology↗

bioRxiv2024

A zinc finger transcriptional repressor ZOS5-09 regulates rice grain size, starch and protein biosynthesis

HighlightA rice seed-preferential transcriptional repressor, ZOS5-09 controls grain size by affecting cell proliferation and expansion; and regulates starch and protein biosynthesis. It acts as a repressor by deacetylation. Grain size is the one of the key determinants of grain yield. Transcription factors form an important class of regulatory proteins that play crucial roles in regulating developmental responses. Our study focuses on a novel seed-preferential C2H2 zinc finger transcription factor, ZOS5-09 (LOC_Os05g38600) that plays an important role in regulating grain related traits in rice. Rice plants with ZOS5-09 promoter::GUS construct showed its high expression in rice endosperm. In planta reporter effector assays and localization studies showed that ZOS5-09 is a nuclear localized transcriptional repressor. It has 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. Plant height, second leaf width, and panicle number were reduced and second leaf length were increased. The change in grain size was due to lower cell proliferation and increased cell size in the transverse direction due to down regulation 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 regulated a seed storage protein encoding gene, GLU6 by binding to the zinc finger binding site in its promoter. It acted as a repressor by promoting deacetylation upon interaction with a histone deacetylase. In summary, our results indicate that 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.

plant biology↗

bioRxiv2023

Two splice forms of OsbZIP1, a homolog of AtHY5, function to regulate skoto- and photo-morphogenesis in rice

Plants possess well-developed light sensing mechanisms and signal transduction systems for regulating photomorphogenesis. ELONGATED HYOCOTYL 5 (HY5), a basic leucine zipper transcription factor, has been extensively characterized in dicot plants. In this study, we have shown that OsbZIP1 is a functional homolog of Arabidopsis HY5 (AtHY5) and is important for light-mediated regulation of seedling and mature plant development in rice. Ectopic expression of OsbZIP1 in rice reduces plant height and leaf length without affecting plant fertility, which is in contrast to OsbZIP48, another HY5 homolog we characterised earlier. OsbZIP1 is alternatively spliced and the isoform OsbZIP1.2 lacking COP1 binding domain regulates seedling development in dark; this is unique since AtHY5 lacking COP1 binding domain does not display such a phenotype. Rice seedlings overexpressing OsbZIP1 were found to be shorter than vector control under white and monochromatic light conditions whereas RNAi seedlings displayed completely opposite phenotype. While OsbZIP1.1 is light regulated, OsbZIP1.2 shows similar protein profile in both light and dark conditions. Due to its interaction with OsCOP1, OsbZIP1.1 undergoes degradation via 26S proteasome under dark conditions. Also, OsbZIP1.1 interacts with CASEIN KINASE 2 (OsCK2[a]3) and consequently undergoes phosphorylation. In comparison, OsbZIP1.2 did not show any interaction with COP1 and OsCK2[a]3. We propose that OsbZIP1.1 most likely works under low fluence of blue light (15 mol/m{superscript 2}/s) while OsbZIP1.2 becomes dominant as the fluence is increased to 30 mol/m{superscript 2}/s. Data presented in this study reveal that AtHY5 homologs in rice have undergone neofunctionalization and alternative splicing (AS) of OsbZIP1 has increased the repertoire of its functions. One sentence summaryAlternative spliced forms of OsbZIP1, an AtHY5 homolog in rice, regulate seedling development in response to light and dark

plant biology↗

bioRxiv2022

GWAShub: A Web-based Resource to Democratize Genome-Wide Association Studies in Crop Plants

Genome-wide association study (GWAS) is a popular approach for linking natural genetic variation with phenotype variation and thus is central to crop quantitative genetics. The ever-increasing wealth of publicly available genomic sequence information for crop plants presents an unprecedented opportunity for utilizing GWAS for the identification of genes governing a plethora of agronomic traits. However, the lack of technical expertise and computational infrastructure is still hindering the ability of plant breeders to conduct GWAS in a self-reliant manner. Here, we present a GWAShub web server that provides a user-friendly interface for performing comprehensive GWAS and post-GWAS in crop plants utilizing publicly available genomic sequence variation data, comprehensive annotation data and diverse computational tools. The utility of GWAS-hub was further demonstrated by conducting large-scale GWAS for flowering/maturity time traits in chickpea. This analysis identified three different flowering/maturity time associated genes, all encoding different histone methyltransferases. Thus, epigenetic regulation is identified as vital mechanism regulating flowering time and maturity duration in chickpea. Finally, we hope GWAShub (www.gwashub.com) will enable resource-scarce researchers to join the GWAS revolution fueled by advancements in next-generation sequencing and computational genomics

bioinformatics↗

bioRxiv2022

Rice Pan-genome Array (RPGA): an efficient genotyping solution for pan-genome-based accelerated crop improvement in rice

The advent of the pan-genome era has unraveled previously unknown genetic variation existing within diverse crop plants including rice. This untapped genetic variation is believed to account for a major portion of phenotypic variation existing in crop plants and might be responsible for missing heritability. However, the use of conventional single reference-guided genotyping often fails to capture large portion of this genetic variation leading to a reference bias. This makes it difficult to identify and utilize novel population/cultivar-specific genes for crop improvement. To overcome this challenge, we developed a rice pan-genome genotyping array (RPGA) includes 80K genome-wide SNPs which provides simple, user-friendly and cost-effective solution for rapid pan-genome-based genotyping in rice. The GWAS conducted using RPGA-SNP genotyping data of a rice diversity panel detected total of 42 loci, including previously known as well as novel genomic loci regulating grain size/weight traits in rice. Eight of the identified trait-associated loci (dispensable loci) could not be detected with conventional single reference genome-based GWAS and found to be missing from the commonly used Nipponbare reference genome. WD repeat-containing PROTEIN 12 gene underlying one of such dispensable locus on chromosome 7 (qLWR7) along with few other non-dispensable loci was subsequently detected using high-resolution QTL mapping confirming authenticity of RPGA-led GWAS. This demonstrates the potential of RPGA-based genotyping to overcome reference bias. Besides GWAS, the application of RPGA-based genotyping for natural allelic diversity and population structure analysis, seed purity and hybridity testing, ultra-high-density genetic map construction and chromosome level genome assembly, and marker-assisted foreground/background selection was successfully demonstrated. Based on these salient outcomes, a web application (http://www.rpgaweb.com) was also developed to provide easy to use platform for imputation of RPGA-based genotyping data using 3K Rice Reference Panel and subsequent GWAS in order to drive genetic improvement of rice.

genomics↗

bioRxiv2021

ImaGene: A web-based software platform for tumor radiogenomic evaluation and reporting

The field of radiomics has undergone several advancements in approaches to uncovering hidden quantitative features from tumor imaging data for use in guiding clinical decision-making for cancer patients. Radiographic imaging techniques provide insight into the imaging features of tumor regions of interest (ROIs), while immunohistochemistry and sequencing techniques performed on biopsy samples yield omics data. Potential associations between tumor genotype and phenotype can be identified from imaging and omics data via traditional correlation analysis, as well as through artificial intelligence (AI) models. However, at present the radiogenomics community lacks a unified software platform for which to conduct such analyses in a reproducible manner. To address this gap, we propose ImaGene, a web-based platform that takes tumor omics and imaging data sets as input, performs correlation analysis between them, and constructs AI models (optionally using only those features found to exhibit statistically significant correlation with some element of the opposing dataset). ImaGene has several modifiable configuration parameters, providing users complete control over their analysis. For each run, ImaGene produces a comprehensive report displaying a number of intuitive model diagnostics. To demonstrate the utility of ImaGene, exploratory studies surrounding Invasive Breast Carcinoma (IBC) and Head and Neck Squamous Cell Carcinoma (HNSCC) on datasets acquired from public databases are conducted. Potential associations are identified between several imaging features and 6 genes: CRABP1, SMTNL2, FABP1, HAS1, FAM163A and DSG1 for IBC, and 4 genes: CEACAM6, NANOG, ACSM2B, and UPK2 for HNSCC. In summary, the software provides researchers with a transparent tool for which to begin radiogenomic analysis and explore possible further directions in their research. We anticipate that ImaGene will become the standard platform for tumor analyses in the field of radiogenomics due to its ease of use, flexibility, and reproducibility, and that it can serve as an enabling centrepoint for an emerging radiogenomic knowledge base.

bioinformatics↗

bioRxiv2019

Genome-wide analysis of polymorphisms identified domestication-associated polymorphism desert carrying important rice grain size/weight QTL

Rice grain size and weight are major determinant 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 germplasm, and their association with domestication shaped evolutionary region is not studied before. To identify genetic basis of grain size/weight two long (LGG) and two short grain genotypes (SGG) were resequenced. LGG (LGR and Pusa Basmati 1121) differentiated from SGG (Sonasal and Bindli) by 504439 SNPs and 78166 InDels. The LRK gene cluster was significantly affected and a truncation mutation in the LRK8 kinase domain was uniquely associated with LGG. Phylogeny with 3000 diverse rice accessions revealed four sequenced genotypes belonged to japonica group and were at the edge of clades indicating source of genetic diversity available in Asian rice population. Five SNPs significantly were associated with grain size/weight and top three SNPs were validated in RIL mapping populations, suggesting this study as a valuable resource for high-throughput genotyping. A contiguous [~]6 Mb polymorphism desert region carrying a major grain weight QTL was identified on chromosome 5 in four sequenced genotypes. Further, among 3000, this region was identified as evolutionary important site with significant positive selection, elevated LD, and multiple selection sweeps, stabilising many domestication-related traits including grain size/weight. The aus group genotype retained more allelic variations in the desert region than japonica and indica, and likely to be one of the differentiation point for aus group. We suggest this desert region as an important evolutionary node that can be selected in breeding programs for improvement of grain yield and quality. All data and analysis can be accessed from RiceSzWtBase database.\n\nSignificance statementBeing an important trait, rice grain size/weight has been under rigorous selection since domestication. However, a link between this trait and domestication is not so directly established. In addition to characterization of novel grain size/weight-associated SNPs, in this study, [~] 6 Mb polymorphism desert region harboring major grain weight QTL was identified on chromosome 5, which turned out to be an evolutionary important site with multiple selection sweeps and introgression events, significantly correlated with domestication-related traits.

plant biology↗