Publications of NIPGR Scientists
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Item Comprehensive genome-wide survey, genomic constitution and expression profiling of the NAC transcription factor family in foxtail millet (Setaria italica L.)(PLOS, 2013) Puranik, Swati; Sahu, Pranav Pankaj; Mandal, Sambhu Nath; Suresh B., Venkata; Parida, Swarup K.; Prasad, ManojThe NAC proteins represent a major plant-specific transcription factor family that has established enormously diverse roles in various plant processes. Aided by the availability of complete genomes, several members of this family have been identified in Arabidopsis, rice, soybean and poplar. However, no comprehensive investigation has been presented for the recently sequenced, naturally stress tolerant crop, Setaria italica (foxtail millet) that is famed as a model crop for bioenergy research. In this study, we identified 147 putative NAC domain-encoding genes from foxtail millet by systematic sequence analysis and physically mapped them onto nine chromosomes. Genomic organization suggested that inter-chromosomal duplications may have been responsible for expansion of this gene family in foxtail millet. Phylogenetically, they were arranged into 11 distinct sub-families (I-XI), with duplicated genes fitting into one cluster and possessing conserved motif compositions. Comparative mapping with other grass species revealed some orthologous relationships and chromosomal rearrangements including duplication, inversion and deletion of genes. The evolutionary significance as duplication and divergence of NAC genes based on their amino acid substitution rates was understood. Expression profiling against various stresses and phytohormones provides novel insights into specific and/or overlapping expression patterns of SiNAC genes, which may be responsible for functional divergence among individual members in this crop. Further, we performed structure modeling and molecular simulation of a stress-responsive protein, SiNAC128, proffering an initial framework for understanding its molecular function. Taken together, this genome-wide identification and expression profiling unlocks new avenues for systematic functional analysis of novel NAC gene family candidates which may be applied for improvising stress adaption in plants.Item The DNA-binding activity of an AP2 protein is involved in transcriptional regulation of a stress-responsive gene, SiWD40, in foxtail millet(Elsevier, 2012) Mishra, Awdhesh Kumar; Puranik, Swati; Bahadur, Ranjit Prasad; Prasad, ManojA differentially expressed transcript, encoding a putative WD protein (Setaria italica WD40; SiWD40), was identified in foxtail millet. Tertiary structure modeling revealed that its C-terminus possesses eight blade β-propeller architecture. Its N-terminal has three α-helices and two 310-helices and was highly induced by different abiotic stresses. The SiWD40:GFP fusion protein was nuclear localized. Promoter analysis showed the presence of many cis-acting elements, including two dehydration responsive elements (DRE). A stress-responsive SiAP2 domain containing protein could specifically bind to these elements in the SiWD40 promoter. Thus, for the first time, we report that DREs probably regulate expression of SiWD40 during envi- ronmental stress. Molecular docking analysis revealed that the circumference of the β‐propeller structure was involved in an interaction with a SiCullin4 protein, supporting the adaptability of SiWD40 to act as a scaf- fold. Our study thus provides a vital clue for near future research on the stress-regulation of WD proteins.Item Electrophoretic mobility shift assay reveals a novel recognition sequence for Setaria italica NAC protein(Landes Bioscience, 2011) Puranik, Swati; Kumar, Karunesh; Srivastava, Prem S.; Prasad, ManojThe NAC (NAM/ATAF1,2/CUC2) proteins are among the largest family of plant transcription factors. Its members have been associated with diverse plant processes and intricately regulate the expression of several genes. Inspite of this immense progress, knowledge of their DNA-binding properties are still limited. In our recent publication,1 we reported isolation of a membrane-associated NAC domain protein from Setaria italica (SiNAC). Transactivation analysis revealed that it was a functionally active transcription factor as it could stimulate expression of reporter genes in vivo. Truncations of the transmembrane region of the protein lead to its nuclear localization. Here we describe expression and purification of SiNAC DNA-binding domain. We further report identification of a novel DNA-binding site, [C/G][A/T][T/A][G/C]TC[C/G][A/T][C/G][G/C] for SiNAC by electrophoretic mobility shift assay. The SiNAC-GST protein could bind to the NAC recognition sequence in vitro as well as to sequences where some bases had been reshuffled. The results presented here contribute to our understanding of the DNA-binding specificity of SiNAC protein.Item cDNA-AFLP analysis reveals differential gene expression in response to salt stress in foxtail millet (Setaria italica L.)(Springer, 2008) Jayaraman, Ananthi; Puranik, Swati; Rai, Neeraj Kumar; Vidapu, Sudhakar; Sahu, Pranav Pankaj; Lata, Charu; Prasad, ManojPlant growth and productivity are affected by various abiotic stresses such as heat, drought, cold, salinity, etc. The mechanism of salt tolerance is one of the most important subjects in plant science as salt stress decreases worldwide agricultural production. In our present study we used cDNA-AFLP technique to compare gene expression profiles of a salt tolerant and a salt-sensitive cultivar of foxtail millet (Seteria italica) in response to salt stress to identify early responsive differentially expressed transcripts accumulated upon salt stress and validate the obtained result through quantitative real-time PCR (qRT-PCR). The expression profile was compared between a salt tolerant (Prasad) and susceptible variety (Lepakshi) of foxtail millet in both control condition (L0 and P0) and after 1 h (L1 and P1) of salt stress. We identified 90 transcript-derived fragments (TDFs) that are differentially expressed, out of which 86 TDFs were classified on the basis of their either complete presence or absence (qualitative variants) and 4 on differential expression pattern levels (quantitative variants) in the two varieties. Finally, we identified 27 non-redundant differentially expressed cDNAs that are unique to salt tolerant variety which represent different groups of genes involved in metabolism, cellular transport, cell signaling, transcriptional regulation, mRNA splicing, seed development and storage, etc. The expression patterns of seven out of nine such genes showed a significant increase of differential expression in tolerant variety after 1 h of salt stress in comparison to salt-sensitive variety as analyzed by qRT-PCR. The direct and indirect relationship of identified TDFs with salinity tolerance mechanism is discussed.
