Veda Krishnan

Enhanced nutraceutical potential of gamma irradiated black soybean extracts.

Radiation processing of soybean, varying in seed coat colour, was carried out at dose levels of 0.25, 0.5 and 1 kGy to evaluate their potential anti-proliferative and cytoprotective effects in an in vitro cell culture system. Irradiated and control black (Kalitur) and yellow (DS9712) soybean extracts were characterized in terms of total phenolics, flavonoids and anthocyanins, especially cyanidin-3-glucoside (C3G). Using an epithelial cell line, BEAS-2B the potential cytoprotective effects of soybean extracts were evaluated in terms of intracellular ROS levels and cell viability. The most relevant scavenging effect was found in Kalitur, with 78% decrease in ROS, which well correlated with a 33% increase in C3G after a 1 kGy dose. Results evidenced a correspondence between in vitro antioxidant activity and a potential health property of black soybean extracts, exemplifying the nutraceutical role of C3G. To our knowledge this study is the first report validating the cytoprotective effects of irradiated black soybean extracts.

Comparative Proteomic and Nutritional Composition Analysis of Independent Transgenic Pigeon Pea Seeds Harboring cry1AcF and cry2Aa Genes and Their Nontransgenic Counterparts

Safety assessment of genetically modified plants is an important aspect prior to deregulation. Demonstration of substantial equivalence of the transgenics compared to their nontransgenic counterparts can be performed using different techniques at various molecular levels. The present study is a first-ever comprehensive evaluation of pigeon pea transgenics harboring two independent cry genes, cry2Aa and cry1AcF. The absence of unintended effects in the transgenic seed components was demonstrated by proteome and nutritional composition profiling. Analysis revealed that no significant differences were found in the various nutritional compositional analyses performed. Additionally, 2-DGE-based proteome analysis of the transgenic and nontransgenic seed protein revealed that there were no major changes in the protein profile, although a minor fold change in the expression of a few proteins was observed. Furthermore, the study also demonstrated that neither the integration of T-DNA nor the expression of the cry genes resulted in the production of unintended effects in the form of new toxins or allergens.

Molecular characterization of inositol pentakisphosphate 2-kinase (GmlPk1) from soybean and its expression pattern in the developing seeds

The principal storage compound of seeds, phytic acid, poses several problems for agriculture due to its antinutritional effects making the development of low phytate crops a prime priority in research. Soybean, with its high nutritive value, wide acceptability and varied usage, but possessing high levels of phytate can be a major target of low phytate research. To this effect, Inositol pentakisphosphate 2-kinase (IPK1) can prove to be critical player given its key role in catalyzing the terminal step of phytate biosynthesis. In this paper, we report the expression profile of GmIPK1 across different tissues and seed development stages, cloning of 1371 bp nucleotide sequence representing the full length cDNA of GmIPK1 and in silico analysis for characterization. Amino acid sequence of GmIPK1 showed much similarity with that of Phaseolus vulgaris and Cicer arietinum. It also showed the presence of the characteristic Ins_P5_2-kinase domain required for catalytic activity. Thus this study provides an initial idea on the molecular characterization of GmIPK1 enzyme for its further in detailed study and subsequent utilization in generating low phyate soybean with enhanced mineral bioavailability.

Exploring the role of Inositol 1,3,4-trisphosphate 5/6 kinase-2 (GmITPK2) as a dehydration and salinity stress regulator in Glycine max (L.) Merr. through heterologous expression in E. coli

Phytic acid (PA) is implicative in a spectrum of biochemical and physiological processes involved in plant stress response. Inositol 1,3,4, Tris phosphate 5/6 kinase (ITPK), a polyphosphate kinase that converts Inositol 1,3,4 trisphosphate to Inositol 1,3,4,5/6 tetra phosphate, averting the inositol phosphate pool towards PA biosynthesis, is a key regulator that exists in four different isoforms in soybean. In the present study, in-silico analysis of the promoter region of ITPKs was done and among the four isoforms, promoter region of GmITPK2 showed the presence of two MYB binding elements for drought inducibility and one for ABA response. Expression profiling through qRT-PCR under drought and salinity stress showed higher expression of GmITPK2 isoform compared to the other members of the family. The study revealed GmITPK2 as an early dehydration responsive gene which is also induced by dehydration and exogenous treatment with ABA. To evaluate the osmo-protective role of GmITPK2, attempts were made to assess the bacterial growth on Luria Broth media containing 200 mM NaCl, 16% PEG and 100 μM ABA, individually. The transformed E. coli BL21 (DE3) cells harbouring the GmITPK2 gene depicted better growth on the media compared to the bacterial cells containing the vector alone. Similarly, the growth of the transformed cells in the liquid media containing 200 mM NaCl, 16% PEG and 100 μM ABA showed higher absorbance at 600 nm compared to control, at different time intervals. The GmITPK2 recombinant E. coli cells showing tolerance to drought and salinity thus demonstrated the functional redundancy of the gene across taxa. The purity and specificity of the recombinant protein was assessed and confirmed through PAGE showing a band of ∼35 kDa on western blotting using Anti- Penta His- HRP conjugate antibody. To the best of our knowledge, the present study is the first report exemplifying the role of GmITPK2 isoform in drought and salinity tolerance in soybean.

Molecular modeling and in silico characterization of GmABCC5: a phytate transporter and potential target for low-phytate crops

Designing low-phytate crops without affecting the developmental process in plants had led to the identification of ABCC5 gene in soybean. The GmABCC5 gene was identified and a partial gene sequence was cloned from popular Indian soybean genotype Pusa16. Conserved domains and motifs unique to ABC transporters were identified in the 30 homologous sequences retrieved by BLASTP analysis. The homologs were analyzed for their evolutionary relationship and physiochemical properties. Conserved domains, transmembrane architecture and secondary structure of GmABCC5 were predicted with the aid of computational tools. Analysis identified 53 alpha helices and 31 beta strands, predicting 60% residues in alpha conformation. A three-dimensional (3D) model for GmABCC5 was developed based on 5twv.1.B (Homo sapiens) template homology to gain better insight into its molecular mechanism of transport and sequestration. Spatio-temporal real-time PCR analysis identified mid-to-late seed developmental stages as the time window for the maximum GmABCC5 gene expression, a potential target stage for phytate reduction. Results of this study provide valuable insights into the structural and functional characteristics of GmABCC5, which may be further utilized for the development of nutritionally enriched low-phytate soybean with improved mineral bioavailability.

Comparative analysis of tocopherol biosynthesis genes and its transcriptional regulation in soybean seeds.

Tocopherols composed of four isoforms (α, β, γ, and δ) and its biosynthesis comprises of three pathways: methylerythritol 4-phosphate (MEP), shikimate (SK) and tocopherol-core pathways regulated by 25 enzymes. To understand pathway regulatory mechanism at transcriptional level, gene expression profile of tocopherol-biosynthesis genes in two soybean genotypes was carried out, the results showed significantly differential expression of 5 genes: 1-deoxy-d-xylulose-5-P-reductoisomerase (DXR), geranyl geranyl reductase (GGDR) from MEP, arogenate dehydrogenase (TyrA), tyrosine aminotransferase (TAT) from SK and γ-tocopherol methyl transferase 3 (γ-TMT3) from tocopherol-core pathways. Expression data were further analyzed for total tocopherol (T-toc) and α-tocopherol (α-toc) content by coregulation network and gene clustering approaches, the results showed least and strong association of γ-TMT3/tocopherol cyclase (TC) and DXR/DXS, respectively, with gene clusters of tocopherol biosynthesis suggested the specific role of γ-TMT3/TC in determining tocopherol accumulation and intricacy of DXR/DXS genes in coordinating precursor pathways toward tocopherol biosynthesis in soybean seeds. Thus, the present study provides insight into the major role of these genes regulating the tocopherol synthesis in soybean seeds.

RETRACTED ARTICLE: Overexpression of thaumatin gene confers enhanced resistance to Alternaria brassicae and tolerance to salinity and drought in transgenic Brassica juncea (L.) Czern

RETRACTED ARTICLE: Overexpression of thaumatin gene confers enhanced resistance to Alternaria brassicae and tolerance to salinity and drought in transgenic Brassica juncea (L.) Czern

Molecular mechanism of Begomovirus evolution and plant defense response

Abstract Viruses depend exclusively on the host cell machinery for their propagation and survival, hence they modulate the host gene expression to suit their needs. The range of interactions between various host and viral factors leads to developmental abnormalities in the host. These interactions can be fine-tuned in the host by modulating gene expression through triggering a defense mechanism and allowing epigenetic modifications. In viral genomes a high rate of mutation adds to the complexity of these interactions and helps in developing adaptation to different hosts.