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    Over-expression of OsHOX24 confers enhanced susceptibility to abiotic stresses in transgenic rice via modulating stress-responsive gene expression
    (Frontiers Media S.A., 2017) Bhattacharjee, Annapurna; Sharma, Raghvendra; Jain, Mukesh
    Homeobox transcription factors play critical roles in plant development and abiotic stress responses. In the present study, we raised rice transgenics over-expressing stress-responsive OsHOX24 gene (rice homeodomain-leucine zipper I sub-family member) and analyzed their response to various abiotic stresses at different stages of development. At the seed germination stage, rice transgenics over-expressing OsHOX24 exhibited enhanced sensitivity to abiotic stress conditions and abscisic acid as compared to wild-type (WT). OsHOX24 over-expression rice seedlings showed reduced root and shoot growth under salinity and desiccation stress (DS) conditions. Various physiological and phenotypic assays confirmed higher susceptibility of rice transgenics toward abiotic stresses as compared to WT at mature and reproductive stages of rice development too. Global gene expression profiling revealed differential regulation of several genes in the transgenic plants under control and DS conditions. Many of these differentially expressed genes were found to be involved in transcriptional regulatory activities, besides carbohydrate, nucleic acid and lipid metabolic processes and response to abiotic stress and hormones. Taken together, our findings highlighted the role of OsHOX24 in regulation of abiotic stress responses via modulating the expression of stress-responsive genes in rice.
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    Microarray analysis reveals overlapping and specific transcriptional responses to different plant hormones in rice
    (Landes Bioscience, 2012) Garg, Rohini; Tyagi, Akhilesh K.; Jain, Mukesh
    Hormones exert pleiotropic effects on plant growth and development throughout the life cycle. Many of these effects are mediated at molecular level via altering gene expression. In this study, we investigated the exogenous effect of plant hormones, including auxin, cytokinin, abscisic acid, ethylene, salicylic acid and jasmonic acid, on the transcription of rice genes at whole genome level using microarray. Our analysis identified a total of 4171 genes involved in several biological processes, whose expression was altered significantly in the presence of different hormones. Further, 28% of these genes exhibited overlapping transcriptional responses in the presence of any two hormones, indicating crosstalk among plant hormones. In addition, we identified genes showing only a particular hormone-specific response, which can be used as hormone-specific markers. The results of this study will facilitate further studies in hormone biology in rice.
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    PlantRGS: a web server for the identification of most suitable candidate reference genes for quantitative gene expression studies in plants
    (Oxford University Press, 2011) Patel, Ravi K.; Jain, Mukesh
    Normalization of quantitative gene expression data with a suitable reference gene is essential for accurate and reliable results. However, the availability and choice of most suitable reference gene(s) showing uniform expression across all the experimental conditions remain a drawback. We have developed a web server, PlantRGS (http://www.nipgr.res.in/PlantRGS), for the identification of most suitable candidate reference gene(s) at the whole-genome level using microarray data for quantitative gene expression studies in plants. Microarray data from more than 11 000 tissue samples for nine plant species have been included in the PlantRGS for meta-analysis. The web server provides a user-friendly graphical user interface-based analysis tool for the identification of most suitable reference genes in the selected plant species under user-defined experimental conditions. Various parameter options and output formats will help users to investigate desired number of most suitable reference genes with wide range of expression levels. Validation of results revealed that novel reference genes identified by the PlantRGS outperforms the traditionally used reference genes in terms of expression stability. We anticipate that the PlantRGS will provide a platform for the identification of most suitable reference gene(s) under given experimental conditions and facilitate quantitative gene expression studies in plants.
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    Role of auxin-responsive genes in biotic stress responses
    (Landes Bioscience, 2009) Ghanashyam, Challa; Jain, Mukesh
    Although the phytohormone auxin has been implicated primarily in developmental processes, some recent studies suggest its involvement in stress/defense responses as well. Recently, we identified auxin-responsive genes and reported their comprehensive transcript profiling during various stages of development and abiotic stress responses in crop plant rice. The analysis revealed tissue-specific and overlapping expression profiles of auxin-responsive genes during various stages of reproductive development. In addition, a large number of auxin-responsive genes were also found to be differentially expressed under various abiotic stress conditions. Here, we further analyze the expression profiles of auxin-responsive genes during various biotic stress conditions. Several auxin-responsive genes showed response to biotic stress as well. Our analysis provides evidence for role of auxin in plant defense responses and suggests cross-talk between auxin, abiotic stress and biotic stress signaling pathways.