Browsing by Author "Pandey, Garima"

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Chromatin-based epigenetic regulation of plant abiotic stress response
(Bentham Science, 2016) Pandey, Garima; Sharma, Namisha; Sahu, Pranav Pankaj; Prasad, Manoj
Plants are continuously exposed to various abiotic and biotic factors limiting their growth and reproduction. In response, they need various sophisticated ways to adapt to adverse environmental conditions without compromising their proper development, reproductive success and eventually survival. This requires an intricate network to regulate gene expression at transcriptional and post-transcriptional levels, including epigenetic switches. Changes in chromatin modifications such as DNA and histone methylation have been observed in plants upon exposure to several abiotic stresses. In the present review, we highlight the changes of DNA methylation in diverse plants in response to several abiotic stresses such as salinity, drought, cold and heat. We also discuss the progresses made in understanding how these DNA methylation changes might contribute to the abiotic stress tolerance.
Development of 5123 intron-length polymorphic markers for large-scale genotyping applications in foxtail millet
(Oxford University Press, 2014) Muthamilarasan, Mehanathan; Venkata Suresh, B.; Pandey, Garima; Kumari, Kajal; Parida, Swarup K.; Prasad, Manoj
Generating genomic resources in terms of molecular markers is imperative in molecular breeding for crop improvement. Though development and application of microsatellite markers in large-scale was reported in the model crop foxtail millet, no such large-scale study was conducted for intron-length polymorphic (ILP) markers. Considering this, we developed 5123 ILP markers, of which 4049 were physically mapped onto 9 chromosomes of foxtail millet. BLAST analysis of 5123 expressed sequence tags (ESTs) suggested the function for ∼71.5% ESTs and grouped them into 5 different functional categories. About 440 selected primer pairs representing the foxtail millet genome and the different functional groups showed high-level of cross-genera amplification at an average of ∼85% in eight millets and five non-millet species. The efficacy of the ILP markers for distinguishing the foxtail millet is demonstrated by observed heterozygosity (0.20) and Nei's average gene diversity (0.22). In silico comparative mapping of physically mapped ILP markers demonstrated substantial percentage of sequence-based orthology and syntenic relationship between foxtail millet chromosomes and sorghum (∼50%), maize (∼46%), rice (∼21%) and Brachypodium (∼21%) chromosomes. Hence, for the first time, we developed large-scale ILP markers in foxtail millet and demonstrated their utility in germplasm characterization, transferability, phylogenetics and comparative mapping studies in millets and bioenergy grass species.
Development of novel microRNA-based genetic markers in foxtail millet for genotyping applications in related grass species
(Springer, 2014) Yadav, Chandra Bhan; Muthamilarasan, Mehanathan; Pandey, Garima; Khan, Yusuf; Prasad, Manoj
DNA markers are important in molecular breeding, and, hence, considering its prominence, a variety of DNA-based molecular markers have been explored and developed for expediting crop improvement programs. microRNA (miRNA)-based molecular marker is a type of functional markers exploited predominantly in animal sciences, but reported in very few plants. Considering the efficacy, stability and transferability potential of the miRNA-based markers, the present study was conducted to develop these markers in the model crop foxtail millet. The pre-miRNA sequences of foxtail millet and other related grasses including rice, maize, wheat, sorghum and Brachypodium were retrieved and aligned for identifying the conserved regions. One hundred and seventy-six primer pairs were designed for these consensus sequences, and all these 176 miRNA-based markers were mapped onto foxtail millet genome. Of the 176 markers, 66 were chosen for further experimentations based on representing the nine chromosomes of foxtail millet and presence of highly conserved regions. All the 66 markers showed 100 % amplification in five cultivars of foxtail millet. Moreover, all the markers showed a higher level of cross-genera transferability potential with an average of ~67 % in millets and non-millet species. This is the first report on the development of novel miRNA-based markers in foxtail millet. Promisingly, these markers would serve as novel genotyping tool for various molecular breeding approaches aiming at crop improvement in millets and non-millet species.
Epigenetic mechanisms of plant stress responses and adaptation
(Springer, 2013) Sahu, Pranav Pankaj; Pandey, Garima; Sharma, Namisha; Puranik, Swati; Muthamilarasan, Mehanathan; Prasad, Manoj
Epigenetics has become one of the hottest topics of research in plant functional genomics since it appears promising in deciphering and imparting stress-adaptive potential in crops and other plant species. Recently, numerous studies have provided new insights into the epigenetic control of stress adaptation. Epigenetic control of stress-induced phenotypic response of plants involves gene regulation. Growing evidence suggest that methylation of DNA in response to stress leads to the variation in phenotype. Transposon mobility, siRNA-mediated methylation and host methyltransferase activation have been implicated in this process. This review presents the current status of epigenetics of plant stress responses with a view to use this knowledge towards engineering plants for stress tolerance.
Epigenetics and epigenomics of plants
(Springer, 2018) Yadav, Chandra Bhan; Pandey, Garima; Muthamilarasan, Mehanathan
The genetic material DNA in association with histone proteins forms the complex structure called chromatin, which is prone to undergo modification through certain epigenetic mechanisms including cytosine DNA methylation, histone modifications, and small RNA-mediated methylation. Alterations in chromatin structure lead to inaccessibility of genomic DNA to various regulatory proteins such as transcription factors, which eventually modulates gene expression. Advancements in high-throughput sequencing technologies have provided the opportunity to study the epigenetic mechanisms at genome-wide levels. Epigenomic studies using high-throughput technologies will widen the understanding of mechanisms as well as functions of regulatory pathways in plant genomes, which will further help in manipulating these pathways using genetic and biochemical approaches. This technology could be a potential research tool for displaying the systematic associations of genetic and epigenetic variations, especially in terms of cytosine methylation onto the genomic region in a specific cell or tissue. A comprehensive study of plant populations to correlate genotype to epigenotype and to phenotype, and also the study of methyl quantitative trait loci (QTL) or epiGWAS, is possible by using high-throughput sequencing methods, which will further accelerate molecular breeding programs for crop improvement.
Genome-wide development and use of microsatellite markers for large-scale genotyping applications in foxtail millet [Setaria italica (L.)]
(Oxford University Press, 2013) Pandey, Garima; Misra, Gopal; Kumari, Kajal; Gupta, Sarika; Parida, Swarup K.; Chattopadhyay, Debasis; Prasad, Manoj
The availability of well-validated informative co-dominant microsatellite markers and saturated genetic linkage map has been limited in foxtail millet (Setaria italica L.). In view of this, we conducted a genome-wide analysis and identified 28 342 microsatellite repeat-motifs spanning 405.3 Mb of foxtail millet genome. The trinucleotide repeats (∼48%) was prevalent when compared with dinucleotide repeats (∼46%). Of the 28 342 microsatellites, 21 294 (∼75%) primer pairs were successfully designed, and a total of 15 573 markers were physically mapped on 9 chromosomes of foxtail millet. About 159 markers were validated successfully in 8 accessions of Setaria sp. with ∼67% polymorphic potential. The high percentage (89.3%) of cross-genera transferability across millet and non-millet species with higher transferability percentage in bioenergy grasses (∼79%, Switchgrass and ∼93%, Pearl millet) signifies their importance in studying the bioenergy grasses. In silico comparative mapping of 15 573 foxtail millet microsatellite markers against the mapping data of sorghum (16.9%), maize (14.5%) and rice (6.4%) indicated syntenic relationships among the chromosomes of foxtail millet and target species. The results, thus, demonstrate the immense applicability of developed microsatellite markers in germplasm characterization, phylogenetics, construction of genetic linkage map for gene/quantitative trait loci discovery, comparative mapping in foxtail millet, including other millets and bioenergy grass species.
Genome-wide development of transposable elements-based markers in foxtail millet and construction of an integrated database
(Oxford University Press, 2015) Yadav, Chandra Bhan; Bonthala, Venkata Suresh; Muthamilarasan, Mehanathan; Pandey, Garima; Khan, Yusuf; Prasad, Manoj
Transposable elements (TEs) are major components of plant genome and are reported to play significant roles in functional genome diversity and phenotypic variations. Several TEs are highly polymorphic for insert location in the genome and this facilitates development of TE-based markers for various genotyping purposes. Considering this, a genome-wide analysis was performed in the model plant foxtail millet. A total of 30,706 TEs were identified and classified as DNA transposons (24,386), full-length Copia type (1,038), partial or solo Copia type (10,118), full-length Gypsy type (1,570), partial or solo Gypsy type (23,293) and Long- and Short-Interspersed Nuclear Elements (3,659 and 53, respectively). Further, 20,278 TE-based markers were developed, namely Retrotransposon-Based Insertion Polymorphisms (4,801, ∼24%), Inter-Retrotransposon Amplified Polymorphisms (3,239, ∼16%), Repeat Junction Markers (4,451, ∼22%), Repeat Junction-Junction Markers (329, ∼2%), Insertion-Site-Based Polymorphisms (7,401, ∼36%) and Retrotransposon-Microsatellite Amplified Polymorphisms (57, 0.2%). A total of 134 Repeat Junction Markers were screened in 96 accessions of Setaria italica and 3 wild Setaria accessions of which 30 showed polymorphism. Moreover, an open access database for these developed resources was constructed (Foxtail millet Transposable Elements-based Marker Database; http://59.163.192.83/ltrdb/index.html). Taken together, this study would serve as a valuable resource for large-scale genotyping applications in foxtail millet and related grass species.
Identification, characterization and expression profiling of Dicer-like, Argonaute and RNA-dependent RNA polymerase gene families in foxtail millet
(Springer, 2015) Yadav, Chandra Bhan; Muthamilarasan, Mehanathan; Pandey, Garima; Prasad, Manoj
Post-transcriptional control of gene expression is achieved through RNA interference where the activities of Dicer-like (DCL), Argonautes (AGO) and RNA-dependent RNA polymerases (RDRs) are significant. Hence, considering the importance of DCL, AGO and RDRs, a comprehensive genome-wide analysis was performed in foxtail millet. The study identified 8 DCL, 19 AGO and 11 RDR genes. Phylogenetic and domain analysis provided interesting information on the evolutionary and structural aspects of these proteins. The orthologs of Setaria italica DCL (SiDCL), AGO (SiAGO) and RDRs (SiRDRs) were identified in sorghum, maize and rice, and the evolutionary relationships among the orthologous gene pairs were investigated. Promoter analysis of SiDCL, SiAGO and SiRDR genes revealed the presence of unique and common cis-acting elements at the upstream of respective gene sequences, which serves as binding sites for several developmental and stress-related transcription factors. In silico expression profiling using RNA-sequence data showed tissue-specific expression patterns of these genes in foxtail millet. Candidate genes representing each sub-family were chosen for expression analysis through quantitative real-time PCR (qRT-PCR) under salinity, dehydration and hormonal treatments. It revealed the differential expression pattern of candidate genes at different time points of stresses. This is the first report on genome-wide analysis of SiDCL, SiAGO and SiRDR gene families in foxtail millet, which provides basic genomic information and insights into the putative roles of these genes in abiotic stresses. The present study will serve as a base for further functional characterization of these gene families in foxtail millet and related grass species.
Salinity induced differential methylation patterns in contrasting cultivars of foxtail millet (Setaria italica L.)
(Springer, 2017) Pandey, Garima; Yadav, Chandra Bhan; Sahu, Pranav Pankaj; Muthamilarasan, Mehanathan; Prasad, Manoj
Reduced productivity and significant yield loss are the adverse effects of environmental conditions on physiological and biochemical pathways in crop plants. In this context, understanding the epigenetic machinery underlying the tolerance traits in a naturally stress tolerant crop is imperative. Foxtail millet (Setaria italica) is known for its better tolerance to abiotic stresses compared to other cereal crops. In the present study, methylation-sensitive amplified polymorphism (MSAP) technique was used to quantify the salt-induced methylation changes in two foxtail millet cultivars contrastingly differing in their tolerance levels to salt stress. The study highlighted that the DNA methylation level was significantly reduced in tolerant cultivar compared to sensitive cultivar. A total of 86 polymorphic MSAP fragments were identified, sequenced and functionally annotated. These fragments showed sequence similarity to several genes including ABC transporter, WRKY transcription factor, serine threonine-protein phosphatase, disease resistance, oxidoreductases, cell wall-related enzymes and retrotransposon and transposase like proteins, suggesting salt stress-induced methylation in these genes. Among these, four genes were chosen for expression profiling which showed differential expression pattern between both cultivars of foxtail millet. Altogether, the study infers that salinity stress induces genome-wide DNA demethylation, which in turn, modulates expression of corresponding genes.