Biomedical subjects

Sneh L Singla-Pareek

Publications and source records attributed to Sneh L Singla-Pareek.

7 recordsLinked to original sources

PubMed2026

Mapping the Molecular Evolution and Role of Wild Rice GLYIII Protein-Encoding Genes in Abiotic Stress Response.

To address the need for sustainable food production amid rapid global climate change, developing rice varieties that grow optimally even under harsh conditions is essential. An effective approach in this direction would be to harness the stress resilience traits of the crop wild relatives (CWRs) of rice. Among the various crucial stress-responsive genes, the Glyoxalase III (GLYIII) gene family is of utmost importance for its ability to detoxify the toxic glycolytic byproduct, methylglyoxal (MG), in a less energy-intensive, single-step process, as well as for its multifaceted cytoprotective role. In our study, a comprehensive genome-wide search across the Oryza genus revealed that GLYIII genes are conserved across wild rice genotypes. Their number has expanded during domestication, driven by gene duplications. Interestingly, only a few orthologous pairs showed positive selection, suggesting that the functions of most others need to be constrained and or conserved.We found that higher GLYIII activity, Total Antioxidant Capacity, endogenous glutathione (GSH) levels, and free radical scavenging activity contributes to the stress resilience of wild rices O. punctata, O. meridionalis, and O. nivara, in addition to other factors. , , . , . Our qRT-PCR analysis revealed differential expression of the OpGLYIII, OmGLYIII, and OnGLYIII genes across different developmental stages and in response to various abiotic stresses. Furthermore, we report that wild rice GLYIII proteins, specifically OpGLYIII-3, OmGLYIII-3, and OnGLYIII-5, exhibit high catalytic efficiency over a broad pH range and at higher temperatures under in vitro assay conditions. Overexpression of these proteins was found to impart substantial stress resilience to the transformed E. coli cells. These findings collectively suggest that GLYIII proteins constitute a key component of the abiotic stress response machinery in wild rice.

Oryza↗

PubMed2006

Whole-genome analysis of Oryza sativa reveals similar architecture of two-component signaling machinery with Arabidopsis.

The two-component system (TCS), which works on the principle of histidine-aspartate phosphorelay signaling, is known to play an important role in diverse physiological processes in lower organisms and has recently emerged as an important signaling system in plants. Employing the tools of bioinformatics, we have characterized TCS signaling candidate genes in the genome of Oryza sativa L. subsp. japonica. We present a complete overview of TCS gene families in O. sativa, including gene structures, conserved motifs, chromosome locations, and phylogeny. Our analysis indicates a total of 51 genes encoding 73 putative TCS proteins. Fourteen genes encode 22 putative histidine kinases with a conserved histidine and other typical histidine kinase signature sequences, five phosphotransfer genes encoding seven phosphotransfer proteins, and 32 response regulator genes encoding 44 proteins. The variations seen between gene and protein numbers are assumed to result from alternative splicing. These putative proteins have high homology with TCS members that have been shown experimentally to participate in several important physiological phenomena in plants, such as ethylene and cytokinin signaling and phytochrome-mediated responses to light. We conclude that the overall architecture of the TCS machinery in O. sativa and Arabidopsis thaliana is similar, and our analysis provides insights into the conservation and divergence of this important signaling machinery in higher plants.

Amino Acid Sequence↗

PubMed2006

Characterization and functional validation of glyoxalase II from rice.

Glyoxalase II, one of the enzymes of the glyoxalase pathway, cDNA cloned from rice (OsglyII) consists of 1623 nucleotides with an open reading frame of 1010 bp encoding a polypeptide of 336 amino acids and an estimated isoelectric point of 8.08. The recombinant protein purified from Escherichia coli using Ni-NTA affinity chromatography showed molecular mass of approximately 37 kDa. Catalytic parameters of the protein were determined using S-D-lactoylglutathione as a thioester substrate. The K(m) (61 microM) and K(cat) (301 s(-1)) values were lower than those reported for Arabidopsis, human and yeast and showed pH optima at 7.2. The E. coli overexpressing OsglyII were able to grow on higher concentration of methylglyoxal. Transcript analysis in rice showed that OsglyII gene expression is stimulated within 15 min in response to various abiotic stresses as well as treatment with abscisic acid or salicylic acid. This multistress response of OsglyII gene documents its future utility in developing tolerance to various stresses in crop plants.

Amino Acid Sequence↗

PubMed2005

Transgenic tobacco overexpressing glyoxalase pathway enzymes grow and set viable seeds in zinc-spiked soils.

We reported earlier that engineering of the glyoxalase pathway (a two-step reaction mediated through glyoxalase I and II enzymes) enhances salinity tolerance. Here we report the extended suitability of this engineering strategy for improved heavy-metal tolerance in transgenic tobacco (Nicotiana tabacum). The glyoxalase transgenics were able to grow, flower, and set normal viable seeds in the presence of 5 mm ZnCl2 without any yield penalty. The endogenous ion content measurements revealed roots to be the major sink for excess zinc accumulation, with negligible amounts in seeds in transgenic plants. Preliminary observations suggest that glyoxalase overexpression could confer tolerance to other heavy metals, such as cadmium or lead. Comparison of relative tolerance capacities of transgenic plants, overexpressing either glyoxalase I or II individually or together in double transgenics, evaluated in terms of various critical parameters such as survival, growth, and yield, reflected double transgenics to perform better than either of the single-gene transformants. Biochemical investigations indicated restricted methylglyoxal accumulation and less lipid peroxidation under high zinc conditions in transgenic plants. Studies employing the glutathione biosynthetic inhibitor, buthionine sulfoximine, suggested an increase in the level of phytochelatins and maintenance of glutathione homeostasis in transgenic plants during exposure to excess zinc as the possible mechanism behind this tolerance. Together, these findings presents a novel strategy to develop multiple stress tolerance via glyoxalase pathway engineering, thus implicating its potential use in engineering agriculturally important crop plants to grow on rapidly deteriorating lands with multiple unfavorable edaphic factors.

Cadmium↗

PubMed2005

Methylglyoxal levels in plants under salinity stress are dependent on glyoxalase I and glutathione.

Methylglyoxal (MG), a cytotoxic by-product produced mainly from triose phosphates, is used as a substrate by glyoxalase I. In this paper, we report on the estimation of MG level in plants which has not been reported earlier. We show that MG concentration varies in the range of 30-75 microM in various plant species and it increases 2- to 6-fold in response to salinity, drought, and cold stress conditions. Transgenic tobacco underexpressing glyoxalase I showed enhanced accumulation of MG which resulted in the inhibition of seed germination. In the glyoxalase I overexpressing transgenic tobacco, MG levels did not increase in response to stress compared to the untransformed plants, however, with the addition of exogenous GSH there was a decrease in MG levels in both untransformed and transgenic plants. The exogenous application of GSH reduced MG levels in WT to 50% whereas in the transgenic plants a 5-fold decrease was observed. These studies demonstrate an important role of glyoxalase I along with GSH concentration in maintaining MG levels in plants under normal and abiotic stress conditions.

Chromatography, High Pressure Liquid↗

PubMed2005

Transgenic tobacco plants overexpressing glyoxalase enzymes resist an increase in methylglyoxal and maintain higher reduced glutathione levels under salinity stress.

The mechanism behind enhanced salt tolerance conferred by the overexpression of glyoxalase pathway enzymes was studied in transgenic vis-à-vis wild-type (WT) plants. We have recently documented that salinity stress induces higher level accumulation of methylglyoxal (MG), a potent cytotoxin and primary substrate for glyoxalase pathway, in various plant species [Yadav, S.K., Singla-Pareek, S.L., Ray, M., Reddy, M.K. and Sopory, S.K. (2005) MG levels in plants under salinity stress are dependent on glyoxalase I and glutathione. Biochem. Biophys. Res. Commun. 337, 61-67]. The transgenic tobacco plants overexpressing glyoxalase pathway enzymes, resist an increase in the level of MG that increased to over 70% in WT plants under salinity stress. These plants showed enhanced basal activity of various glutathione related antioxidative enzymes that increased further upon salinity stress. These plants suffered minimal salinity stress induced oxidative damage measured in terms of the lipid peroxidation. The reduced glutathione (GSH) content was high in these transgenic plants and also maintained a higher reduced to oxidized glutathione (GSH:GSSG) ratio under salinity. Manipulation of glutathione ratio by exogenous application of GSSG retarded the growth of non-transgenic plants whereas transgenic plants sustained their growth. These results suggest that resisting an increase in MG together with maintaining higher reduced glutathione levels can be efficiently achieved by the overexpression of glyoxalase pathway enzymes towards developing salinity stress tolerant plants.

Antioxidants↗

PubMed2003

A signal peptide secretion screen in Fucus distichus embryos reveals expression of glucanase, EGF domain-containing, and LRR receptor kinase-like polypeptides during asymmetric cell growth.

Zygotes of the brown alga Fucus distichus (L.) Powell develop polarity prior to the first embryonic cell division and retain a pattern of asymmetric growth during early embryogenesis. In order to identify F. distichus polypeptides secreted during asymmetric cell growth, we used a functional assay in Saccharomyces cerevisiae to screen a cDNA library generated from asymmetrically growing Fucus embryos for sequences encoding polypeptides that function as signal peptides for secretion. We isolated and sequenced 222 plasmids containing Fucus cDNAs encoding signal peptide activity. The cDNA inserts from these plasmids were translated in silico into 244 potential polypeptide sequences, 169 of which are predicted to contain signal peptides. BlastP analysis of the Fucus sequences revealed similarity between many Fucus proteins and cell surface proteins that function in development in other eukaryotes, including epidermal growth factor (EGF)-like repeat-containing proteins, plant leucine-rich repeat (LRR)-receptor kinases, and algal beta-1, 3-exoglucanase. However, most of the isolated Fucus polypeptides lack similarity to known proteins. The isolation of cDNAs encoding secreted Fucus proteins provides an important step toward characterizing cell surface proteins important for asymmetric organization and growth in fucoid embryos.

Amino Acid Sequence↗