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Item Role of chromatin modification and remodeling in stem cell regulation and meristem maintenance in Arabidopsis(Oxford University Press, 2020) Singh, Sharmila; Singh, Alka; Singh, Archita; Mahima; Yadav, Sandeep; Bajaj, Ishita; Kumar, Shailendra; Jain, Ajay; Sarkar, Ananda K.In higher plants, pluripotent stem cells reside in the specialized microenvironment called stem cell niches (SCNs) harbored at the shoot apical meristem (SAM) and root apical meristem (RAM), which give rise to the aerial and underground parts of a plant, respectively. The model plant Arabidopsis thaliana (Arabidopsis) has been extensively studied to decipher the intricate regulatory mechanisms involving some key transcriptions factors and phytohormones that play pivotal roles in stem cell homeostasis, meristem maintenance, and organ formation. However, there is increasing evidence to show the epigenetic regulation of the chromatin architecture, gene expression exerting an influence on an innate balance between the self-renewal of stem cells, and differentiation of the progeny cells to a specific tissue type or organ. Post-translational histone modifications, ATP-dependent chromatin remodeling, and chromatin assembly/ disassembly are some of the key features involved in the modulation of chromatin architecture. Here, we discuss the major epigenetic regulators and illustrate their roles in the regulation of stem cell activity, meristem maintenance, and related organ patterning in Arabidopsis.Item Auxin signaling modulates LATERAL ROOT PRIMORDIUM1 (LRP1) expression during lateral root development in Arabidopsis(John Wiley & Sons, 2020) Singh, Sharmila; Yadav, Sandeep; Singh, Alka; Mahima; Singh, Archita; Gautam, Vibhav; Sarkar, Ananda K.Auxin signaling mediated by various Auxin/Indole-3-Acetic Acid (Aux/IAAs) and AUXIN RESPONSE FACTORs (ARFs) regulate lateral root (LR) development by controlling the expression of downstream genes. LATERAL ROOT PRIMORDIUM1 (LRP1), a member of SHORT INTERNODES/STYLISH (SHI/STY) family, was identified as an auxin inducible gene. Precise developmental role and molecular regulation of LRP1 in root development remains to be understood. Here we show that LRP1 is expressed in all stages of LR development, besides primary root. The expression of LRP1 is regulated by histone deacetylation in an auxin dependent manner. Our genetic interaction studies showed that LRP1 acts downstream of auxin responsive Aux/IAAs-ARFs modules during LR development. We showed that auxin mediated induction of LRP1 is lost in slr-1 and arf7arf19 mutants roots. NPA treatment studies showed that LRP1 acts after LR founder cell specification and asymmetric division. Overexpression of LRP1 (LRP1 OE) showed increased number of LRPs at stage I, IV and V, resulting in reduced emerged LR density, which suggests that it is involved in LRP development. Interestingly, LRP1 induced expression of YUC4, which is involved in auxin biosynthesis, contributes to increased accumulation of endogenous auxin in LRP1 OE roots. LRP1 interacts with SHI, STY1, SRS3 and SRS7 proteins of SHI/STY family indicating their possible redundant role during root development. Our results suggest that auxin and histone deacetylation affect LRP1 expression, and it acts downstream of LR forming auxin response modules to negatively regulate LRP development by modulating auxin homeostasis in Arabidopsis thaliana.Item Whole mount in situ localization of miRNAs and target mRNA transcripts in plants(Springer Nature Publishing AG, 2019) Gautam, Vibhav; Singh, Archita; Verma, Swati; Singh, Sharmila; Chatterjee, Sourav; Sarkar, Ananda K.The functional characterization of miRNAs often involves understanding of their spatiotemporal expression, which mostly relies on reporter-based or in situ hybridization studies. The available in situ localization methods follow separate protocols for pre-hybridization, hybridization, post-hybridization, and detection steps for both miRNA and mRNA transcripts in plants. In this study, we present a single method which can be used for whole mount in situ localization of both miRNAs and mRNAs in different plant tissues. Our modified method provides enhanced sensitivity for the localization of miRNA and their target transcripts. Consequently, a less laborious, time-saving, economic and efficient method has been proposed by the modification of pre-hybridization, hybridization, post-hybridization and detection steps.Item SWP1 negatively regulates lateral root initiation and elongation in Arabidopsis(Landes Bioscience, 2012) Singh, Sharmila; Singh, Archita; Roy, Shradha; Sarkar, Ananda K.The main root and continuously emerging lateral roots constitute the root architecture of an adult plant during its postembryonic development. Epigenetic modifications like methylation or deacetylation of histones have been suggested to regulate root development. SWP1/LDL1, a component of plant specific corepressor complex, has been implicated in the induction of flowers and root through histone modifications in Arabidopsis. However, molecular role of SWP1 in regulating the lateral root development remained unexplored. Here we show that SWP1 regulates lateral root initiation and elongation in Arabidopsis. Mutation in SWP1 increases both the density and length of lateral roots. SWP1 negatively regulates lateral root initiation through direct/indirect transcriptional repression of lateral root promoting factors, such as AUXIN RESPONSE FACTORS (ARFs) and GATA23.