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Author: search.filters.author.Sarkar, Ananda K.Subject: search.filters.subject.Arabidopsis thaliana

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    Role of miRNAs in root development of model plant Arabidopsis thaliana
    (Springer, 2017) Gautam, Vibhav; Singh, Archita; Verma, Swati; Kumar, Ashutosh; Kumar, Pramod; Mahima; Singh, Sharmila; Mishra, Vishnu; Sarkar, Ananda K.
    The molecular regulation of root development is relatively well studied in model plant Arabidopsis as compared to other plants. Besides phytohormones, transcription factors and environmental factors, other important regulators which have recently been shown to play crucial roles in controlling root development are the non-coding RNAs. Small non-coding RNAs of 21–24 nt length (miRNAs and ta-siRNAs) regulate various aspects of plant development by negatively regulating their target genes through transcript cleavage or translational inhibition. In recent past the microRNA-mediated regulation of root development has drawn significant interest in the area of plant research. Several reports have highlighted the role of many miRNAs and ta-siRNAs in root growth, vascular patterning, lateral root (LR) formation and elongation, and adventitious root development, Phytohormones like auxin, cytokinin and environmental factors like light, abiotic and biotic stresses, and nutrient availability influence many miRNA-mediated regulation of root growth and branching. In current review, we summarize the recent advances made in understanding the miRNA-mediated regulation of root development in the model plant Arabidopsis thaliana. The molecular crosstalk between different miRNAs, ta-siRNAs, and concerned target genes that regulate root growth and branching have been addressed.
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    Phytohormonal crosstalk modulates the expression of miR166/165s, target Class III HD-ZIPs, and KANADI genes during root growth in Arabidopsis thaliana
    (Nature Publishing Group, 2017) Singh, Archita; Roy, Shradha; Singh, Sharmila; Das, Shabari Sarkar; Gautam, Vibhav; Yadav, Sandeep; Kumar, Ashutosh; Singh, Alka; Samantha, Sukanya; Sarkar, Ananda K.
    Both phytohormones and non-coding microRNAs (miRNAs) play important role in root development in Arabidopsis thaliana. Mature miR166/165 s, which are derived from precursor transcripts of concerned genes, regulate developmental processes, including leaf and root patterning, by targeting Class III HOMEODOMAIN LEUCINE-ZIPPER (HD-ZIP III) transcription factors (TFs). However, their regulation through hormones remained poorly understood. Here, we show that several phytohormones dynamically regulate the spatio-temporal expression pattern of miR166/165 and target HD-ZIP IIIs in developing roots. Hormone signaling pathway mutants show differential expression pattern of miR166/165, providing further genetic evidence for multilayered regulation of these genes through phytohormones. We further show that a crosstalk of at least six different phytohormones regulate the miR166/165, their target HD-ZIP IIIs, and KANADI (KANs). Our results suggest that HD-ZIP IIIs mediated root development is modulated both transcriptionally through phytohormones and KANs, and post-transcriptionally by miR166/165 that in turn are also regulated by the phytohormonal crosstalk.
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    Sirtinol, a Sir2 protein inhibitor, affects stem cell maintenance and root development in Arabidopsis thaliana by modulating auxin-cytokinin signaling components
    (Nature Publishing Group, 2017) Singh, Sharmila; Singh, Alka; Yadav, Sandeep; Gautam, Vibhav; Singh, Archita; Sarkar, Ananda K.
    In Arabidopsis thaliana, besides several key transcription factors and chromatin modifiers, phytohormones auxin and cytokinin play pivotal role in shoot and root meristem maintenance, and lateral root (LR) development. Sirtinol, a chemical inhibitor of Sir2 proteins, is known to promote some auxin induced phenotypes in Arabidopsis. However, its effect on plant stem cell maintenance or organ formation remained unaddressed. Here we show that sirtinol affects meristem maintenance by altering the expression of key stem cell regulators, cell division and differentiation by modulating both auxin and cytokinin signaling in Arabidopsis thaliana. The expression of shoot stem cell niche related genes WUSCHEL (WUS) and CLAVATA3 (CLV3) was upregulated, whereas SHOOT MERISTEMLESS (STM) was downregulated in sirtinol treated seedlings. The expression level and domain of key root stem cell regulators PLETHORA (PLTs) and WUS-Related Homeobox 5 (WOX5) were altered in sirtinol treated roots. Sirtinol affects LR development by disturbing proper auxin transport and maxima formation, similar to 2,4-dichlorophenoxyacetic acid (2,4-D). Sirtinol also affects LR formation by altering cytokinin biosynthesis and signaling genes in roots. Therefore, sirtinol affects shoot and root growth, meristem maintenance and LR development by altering the expression of cytokinin-auxin signaling components, and regulators of stem cells, meristems, and LRs.
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    Apple CALCINEURIN B-LIKE PROTEIN10 genes have evolved to be novel targets of miR167s through sequence variation
    (Current Science Association, 2017) Kumar, Ashutosh; Sarkar, Ananda K.
    The miR167s and its target ARF6/8 are relatively conserved among diverse plant species and have been implicated in reproductive and root development in Arabidopsis. Here we show that some of the CNBL family members have evolved to be targets of miR167s in apple. Despite strong conservation between apple and Arabidopsis CNBLs, AtCNBLs are not miR167 targets. The sequence variation in apple-miR167a and MdCNBLs has created target sites for apple-miR167a in MdCNBL10s. Therefore, we suggest that during the course of evolution, natural selection through sequence variation played a crucial role by choosing different targets among plant species for the same miRNA.
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    Iron availability affects phosphate deficiency-mediated responses, and evidences of cross talk with auxin and zinc in Arabidopsis
    (Oxford University Press, 2015) Rai, Vandna; Sanagala, Raghavendrarao; Sinilal, Bhaskaran; Yadav, Sandeep; Sarkar, Ananda K.; Dantu, Prem Kumar; Jain, Ajay
    Phosphate (Pi) is pivotal for plant growth and development. Pi deficiency triggers local and systemically regulated adaptive responses in Arabidopsis thaliana. Inhibition of primary root growth (PRG) and retarded development of lateral roots (LRs) are typical local Pi deficiency-mediated responses of the root system. Expression of Pi starvation-responsive (PSR) genes is regulated systemically. Here, we report the differential influence of iron (Fe) availability on local and systemic sensing of Pi by Arabidopsis. P-Fe- condition disrupted local Pi sensing, resulting in an elongated primary root (PR). Altered Fe homeostasis in the lpsi mutant with aberration in local Pi sensing provided circumstantial evidence towards the role of Fe in the maintenance of Pi homeostasis. Reporter gene assays, expression analysis of auxin-responsive genes (ARGs) and root phenotyping of the arf7arf19 mutant demonstrated the role of Fe availability on local Pi deficiency-mediated LR development. In addition, Fe availability also exerted a significant influence on PSR genes belonging to different functional categories. Together, these results demonstrated a substantial influence of Fe availability on Pi deficiency-mediated responses of ontogenetically distinct traits of the root system and PSR genes. The study also provided evidence of cross-talk between Pi, Fe and Zn, highlighting a complex tripartite interaction amongst them for maintaining Pi homeostasis.