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Author: search.filters.author.Tyagi, Akhilesh K.Subject: search.filters.subject.microarray

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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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    Comparative transcript profiling of TCP family genes provide insight into gene functions and diversification in rice and Arabidopsis
    (Academy Journals, 2010) Sharma, Rita; Kapoor, Meenu; Tyagi, Akhilesh K.; Kapoor, Sanjay
    Plant-specific TCP transcription factor family has been implicated in diverse aspects of growth and development. Rice and Arabidopsis genomes encode 26 and 24 TCP family genes, respectively. In this study, we have performed an inclusive analysis of their expression during 21 and 18 stages of development in rice and Arabidopsis, respectively. The assorted patterns of expression, exhibited by TCP family genes, provide an evidence for spatiotemporal regulation of their relative abundance throughout plant development. Further profiling of rice genes in three sub-stages of early panicle development revealed differential accumulation of nine genes during panicle initiation and organ development. QPCR-based expression profiling of selected rice genes, during four stages of anther, suggested their involvement in early anther development as well. Eleven genes of rice and seven of Arabidopsis were differentially expressed in response to three abiotic stress treatments viz., cold, dehydration and salt. In silico analysis of 5' regulatory regions of differentially expressed genes revealed the presence of previously characterized cis-regulatory elements. Duplications seem to have played major role in diversification of TCP family genes with 14 genes of rice and 10 of Arabidopsis lying on duplicated segments of the respective genomes. Most of the duplicated genes exhibited varied expression patterns. The knowledge obtained in this study will be useful for selection and assessment of the functions of individual genes using reverse genetics approaches.
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    Glycinebetine-induced water-stress tolerance in Cod A-expressing transgenic India rice is associated with up-regulation of several stress responsive genes
    (Wiley-Blackwell, 2009) Kathuria, Hitesh; Giri, Jitender; Nataraja, Karaba N.; Murata, Norio; Udayakumar, Makarla; Tyagi, Akhilesh K.
    Rice (Oryza sativa L.), a non-accumulator of glycinebetaine (GB), is highly susceptible to abiotic stress. Transgenic rice with chloroplast-targeted choline oxidase encoded by the codA gene from Arthrobacter globiformis has been evaluated for inheritance of transgene up to R5 generation and water-stress tolerance. During seedling, vegetative and reproductive stages, transgenic plants could maintain higher activity of photosystem II and they show better physiological performance, for example, enhanced detoxification of reactive oxygen species compared to wild-type plants under water-stress. Survival rate and agronomic performance of transgenic plants is also better than wild-type following prolonged water-stress. Choline oxidase converts choline into GB and H2O2 in a single step. It is possible that H2O2/GB might activate stress response pathways and prepare transgenic plants to mitigate stress. To check this possibility, microarray-based transcriptome analysis of transgenic rice has been done. It unravelled altered expression of many genes involved in stress responses, signal transduction, gene regulation, hormone signalling and cellular metabolism. Overall, 165 genes show more than two-fold up-regulation at P-value < 0.01 in transgenic rice. Out of these, at least 50 genes are known to be involved in plant stress response. Exogenous application of H2O2 or GB to wild-type plants also induces such genes. Our data show that metabolic engineering for GB is a promising strategy for introducing stress tolerance in crop plants and which could be imparted, in part, by H2O2- and/or GB-induced stress response genes.