Biology subjects

Chauhan, H.

Publications and source records attributed to Chauhan, H..

3 recordsLinked to original sources

bioRxiv2023

Characterization and Expression Analysis of Nitrate Reductase 6-1ABD Gene in Hexaploid Bread Wheat Under Different Nitrogen Regime

Nitrate reductase (NR) is the key rate-limiting enzyme of the nitrogen (N) assimilation process in plants, which has not been characterized in bread wheat under nitrogen stress, especially with respect to their homeologues. Total 9 NRs were identified and classified into 3 groups, which showed a close relationship with different wheat ancestors. The occurrence of N-responsive cis-acting regulatory elements like MYB, MYC, G-Box and GATA-motif confirmed their N-responsiveness. Expression of all the three groups of NR under N-stress revealed NR 6-1ABD group to be the most N-responsive, which was characterized further in detail. The study was carried out in two genotypes contrasting for their N-responsiveness (HD 2967: Highly responsive to applied N, and Choti Lerma: Less responsive to applied N) selected on the basis of field evaluation. Homeologous differences within a genotype were found much more than the genotypic differences of a specific homeologue coding sequence. Among the three homeologues, though NR 6-1D homeologue was found most responsive to N-stress, the contribution was maximum for this homeologue followed by NR 6-1A and least by NR 6-1B. We found that the expression of homeologues was linked to the presence of N-responsive cis- elements. All the homeologues of NR 6-1 in Choti Lerma were found less responsive to N-stress, in comparison to HD 2967, which might also be linked to N-use efficiency. Homeologous expression of NR 6-1ABD revealed negligible contribution of B-homeologue to N-stress. Homeologous differences of NR 6-1ABD was found much more than the genotypic differences. Hence, our study on wheat NR will be helpful in manipulating the specific homeologue of the NR gene in the future.

plant biology↗

bioRxiv2022

Chloroplast activity provides in vitro regeneration capability in contrasting cultivars

Existence of potent in vitro regeneration system is a prerequisite for efficient genetic transformation and functional genomics of crop plants. We know little about why only some cultivars in crop plants are tissue culture friendly. In this study, tissue culture friendly cultivar Golden Promise (GP) and tissue culture resistant DWRB91(D91) were selected as contrasting cultivars to investigate the molecular basis of regeneration efficiency. Multiomics studies involving transcriptomics, proteomics, metabolomics, and biochemical analysis were performed using GP and D91 callus to unravel the regulatory mechanisms. Transcriptomics analysis revealed 1487 differentially expressed genes (DEGs), in which 795 DEGs were upregulated and 692 DEGs were downregulated in the GP-D91 transcriptome. Genes encoding proteins localized in chloroplast and involved in ROS generation were upregulated in the embryogenic calli of GP. Moreover, proteome analysis by LC-MSMS revealed 3062 protein groups and 16989 peptide groups, out of these 1586 protein groups were differentially expressed proteins (DEPs). Eventually, GC-MS based metabolomics analysis also revealed the higher activity of plastids and alterations in key metabolic processes such as sugar metabolism, fatty acid biosynthesis, and secondary metabolism. Higher accumulation of sugars, amino acids and metabolites corresponding to lignin biosynthesis were observed in GP as compared to D91. HighlightsMulti omics analysis revealed chloroplast play crucial role in providing in vitro regeneration capability in contrasting genotypes

plant biology↗

bioRxiv2020

Processive Dynamics of the Usher Assembly Platform During Uropathogenic Escherichia coli P Pilus Biogenesis

Uropathogenic Escherichia coli (UPEC) assemble hair-like surface structures termed pili or fimbriae to initiate infection of the urinary tract. P pili mediate the adherence of UPEC to the kidney epithelium, facilitating bacterial colonization and pyelonephritis1. P pili are assembled through the conserved chaperone-usher (CU) pathway2-4. In this pathway, a dedicated chaperone facilitates the folding of nascent pilus subunits in the periplasm and an integral outer membrane (OM) protein termed the usher provides the assembly platform and secretion channel for the pilus fiber. Much of the structural and functional understanding of the CU pathway has been gained through investigations of type 1 pili, which promote UPEC binding to the bladder epithelium and the development of cystitis5. In contrast, the structural basis for P pilus biogenesis at the usher has remained elusive. This is in part due to the flexible and variable-length P pilus tip fiber, creating structural heterogeneity, as well as difficulties in isolating stable P pilus assembly intermediates from bacteria. Here, we have devised a method to circumvent these hindrances and determined cryo-EM structures of the activated PapC usher in the process of secreting two- and three-subunit P pilus assembly intermediates. These structures show processive steps in P pilus biogenesis, reveal differences between P and type 1 pili, and capture new conformational dynamics of the usher assembly machine.

microbiology↗