Browsing by Author "Karmakar, Prakash"

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    Expression dynamics of miRNAs and their targets in seed germination conditions reveals miRNA-ta-siRNA crosstalk as regulator of seed germination
    (Nature Publishing Group, 2018) Das, Shabari Sarkar; Yadav, Sandeep; Singh, Archita; Gautam, Vibhav; Sarkar, Ananda K.; Nandi, Asis K.; Karmakar, Prakash; Majee, Manoj; Sanan-Mishra, Neeti
    Seed germination paves the way for the dormant embryo to establish itself as a new plant marking the first critical step in postembryonic plant growth and development. Germination starts with the uptake of water (imbibition), followed by induction of transcription, translation, energy metabolism, and cell division processes. Although small RNAs have been implicated in many developmental processes, their role during seed germination stages and conditions remained elusive. Here we show that seed germination conditions, like imbibition and temperature, dynamically regulate the expression of many developmentally important miRNAs and their targets. We have identified 58 miRNAs belonging to 30 different families at different seed germination conditions. Amongst these, 15 miRNAs and their targets were significantly differentially expressed in Arabidopsis seeds in dry and 12 h, 24 h and 48 h of imbibition. Interestingly, differential expression of miR390, which targets trans-acting siRNA locus (TAS3) derived transcripts, resulted in alteration of tasiR-ARF mediated regulation of expression of target AUXIN RESPONSE FACTORs (ARF2/3/4). Our results suggest that the dynamic expression of several miRNAs, their targets, and a crosstalk between miRNA and ta-siRNA pathways contribute to the regulation of seed germination in Arabidopsis thaliana.
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    Sequestering miR165/166 enhances seed germination in Arabidopsis thaliana under normal condition and ABA treatment
    (Springer Nature Publishing AG, 2020) Sarkar Das, Shabari; Majee, Manoj; Nandi, Asis K.; Karmakar, Prakash
    Seed germination is a dynamic process involving imbibition, increased metabolic activity and protrusion of a tiny plantlet rupturing the seed coat. Many genes, phytohormones like ABA and GA have been implicated in germination of Arabidopsis thaliana seeds. Although many microRNAs (miRNAs) have been shown to be differentially expressed during seed germination process, their role remains mostly unaddressed. Here we address the role of developmentally important miR165/166 in the process of seed germination. We demonstrate that the seeds of transgenic A. thaliana having target mimic-miR165/166 (eTM-miR165/166), where miR165/166 is sponged, show better germination efficiency. The seeds of this line also maintain better germination even under ABA treatment, which is a negative regulator of seed germination. Thus, our results suggest that, sequestering miR165/166 activity enhances seed germination efficiency under normal and ABA-stress condition.