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1.
Int J Biol Macromol ; 195: 207-216, 2022 Jan 15.
Article in English | MEDLINE | ID: mdl-34890636

ABSTRACT

Pearl millet is a nutrient dense and gluten free cereal, however it's flour remains underutilized due to the onset of rancidity during its storage. To the best of our knowledge, processing methods, which could significantly reduce the rancidity of the pearl millet flour during storage, are non-existent. In this study, pearl millet grains were subjected to a preliminary hydro-treatment (HT). Subsequently, the hydrated grain-wet flour have undergone individual and combined thermal treatments viz., hydrothermal (HTh) and thermal near infrared rays (thNIR). Effects of these thermal treatments on the biochemical process of hydrolytic and oxidative rancidity were analyzed in stored flour. A significant (p < 0.05) decrease in the enzyme activities of lipase (47.8%), lipoxygenase (84.8%), peroxidase (98.1%) and polyphenol oxidase (100%) in HT-HTh-thNIR treated flour compared to the individual treatments was documented. Upon storage (90 days), decline of 67.84% and 66.4% of free fatty acid and peroxide contents were observed in flour under HT-HTh-thNIR treatment without altering starch and protein digestibility properties. HT-HTh treated flour exhibited the highest (7.6%) rapidly digestible starch, decreased viscosity and increased starch digestibility (67.17%). FTIR analysis of HT-HTh treated flour divulged destabilization of short-range ordered crystalline structure and altered protein structures with decreased in vitro digestibility of protein. Overall, these results demonstrated the effectiveness of combined thermal treatment of HT-HTh-thNIR in reducing rancidity and preserving the functional properties of the stored flour.


Subject(s)
Food Handling/methods , Pennisetum/metabolism , Starch/chemistry , Catechol Oxidase , Digestion , Edible Grain , Flour/analysis , Hot Temperature , Lipoxygenase
2.
Planta ; 252(4): 51, 2020 Sep 17.
Article in English | MEDLINE | ID: mdl-32940767

ABSTRACT

MAIN CONCLUSION: Tomato leaf curl New Delhi virus-derived AC4 protein interacts with host proteins involved in auxin biosynthesis and reprograms auxin biosynthesis/signaling to help in viral replication and manifestation of the disease-associated symptoms. Perturbations of phytohormone-mediated gene regulatory network cause growth and developmental defects. Furthermore, plant viral infections cause characteristic disease symptoms similar to hormone-deficient mutants. Tomato leaf curl New Delhi Virus (ToLCNDV)-encoded AC4 is a small protein that attenuates the host transcriptional gene silencing, and aggravated disease severity in tomato is correlated with transcript abundance of AC4. Hence, investigating the role of AC4 in pathogenesis divulged that ToLCNDV-AC4 interacted with host TAR1 (tryptophan amino transferase 1)-like protein, CYP450 monooxygenase-the key enzyme of indole acetic acid (IAA) biosynthesis pathway-and with a protein encoded by senescence-associated gene involved in jasmonic acid pathway. Also, ToLCNDV infection resulted in the upregulation of host miRNAs, viz., miR164, miR167, miR393 and miR319 involved in auxin signaling and leaf morphogenesis concomitant with the decline in endogenous IAA levels. Ectopic overexpression of ToLCNDV-derived AC4 in tomato recapitulated the transcriptomic and disruption of auxin biosynthesis/signaling features of the infected leaves. Furthermore, exogenous foliar application of IAA caused remission of the characteristic disease-related symptoms in tomato. The roles of ToLCNDV-AC4 in reprogramming auxin biosynthesis, signaling and cross-talk with JA pathway to help viral replication and manifest the disease-associated symptoms during ToLCNDV infection are discussed.


Subject(s)
Geminiviridae , Indoleacetic Acids , Solanum lycopersicum , Geminiviridae/pathogenicity , Indoleacetic Acids/metabolism , Solanum lycopersicum/genetics , Solanum lycopersicum/virology , Plant Diseases/virology , Signal Transduction/genetics
3.
3 Biotech ; 10(3): 110, 2020 Mar.
Article in English | MEDLINE | ID: mdl-32099748

ABSTRACT

Gamma-tocopherol methyltransferase (γ-TMT) converts γ-toc to α-toc-the rate limiting step in toc biosynthesis. Sequencing results revealed that the coding regions of γ-TMT1 and γ-TMT3 were strongly similar to each other (93% at amino acid level). Based on the differences in the N-terminal amino acids, Glycine max-γ-TMT proteins are categorized into three isoforms: γ-TMT1, 2 and 3. In silico structural analysis revealed the presence of chloroplast transit peptide (cTP) in γ-TMT1 and γ-TMT3 protein. However, other properties of transit peptide like presence of hydrophobic amino acids at the first three positions of N-terminal end and lower level of acidic amino acids were revealed only in γ-TMT3 protein. Subcellular localization of GFP fused γ-TMT1 and γ-TMT3 under 35S promoter was studied in Nicotiana benthamiana using confocal microscopy. Results showed that γ-TMT1 was found in the cytosol and γ-TMT3 was found to be localized both in cytosol and chloroplast. Further the presence γ-TMT3 in chloroplast was validated by quantifying α-tocopherol through UPLC. Thus the present study of cytosolic localization of the both γ-TMT1 and γ-TMT3 proteins and chloroplastic localization of γ-TMT3 will help to reveal the importance of γ-TMT encoded α-toc in protecting both chloroplastic and cell membrane from plant oxidative stress.

4.
Plant Physiol Biochem ; 144: 375-385, 2019 Nov.
Article in English | MEDLINE | ID: mdl-31622940

ABSTRACT

Soybeans are known for its good source of protein (40%), oil (20%) and also serve as a source of nutraceutical compounds including tocopherols (toc). To know the molecular basis of differential α-toc accumulation in two contrasting soybean genotypes: DS74 (low α-toc - 1.36 µg/g and total-toc -29.72 µg/g) and Bragg (high α-toc - 10.48 µg/g and total-toc 178.91 µg/g), the analysis of γ-TMT3 promoter activity and its methylation patterns were carried out. The sequencing results revealed nucleotide variation between Bragg:γ-TMT3-P and DS74:γ-TMT3-P, however none of the variations were found in core-promoter region or in cis-elements. The histochemical GUS assay revealed higher promoter activity of Bragg:γ-TMT3-P than that of DS74:γ-TMT3-P and correlated with significantly higher and lower (P < 0.05) expression of γ-TMT3 gene respectively. To know the molecular basis of differential accumulation of α-toc in these contrasting soybean genotypes, the DNA methylation pattern of γ-TMT3 gene body and its promoter was studied in both varieties. The results showed higher percentage (62.5%) of methylation in DS74:γ-TMT3-P than in Bragg:γ-TMT3-P (50%). Out of all the methylation sites in the promoter region, one of methylation site was found at CAAT box (-190 bp) of DS74:γ-TMT3-P. Further gene body methylation patterns revealed lowest % (40%) of CG methylation in DS74:γ-TMT3 gene as compared to Bragg:γ-TMT3 (64.2%). Thus our study revealed that, expression of γ-TMT3 gene was influenced by its promoter activity and methylation patterns in cis-elements of γ-TMT3 promoter and gene body. This study will help us to understand the possible role of methylation and promoter activity in determining the α-toc content in soybean seeds.


Subject(s)
Glycine max/metabolism , Tocopherols/metabolism , alpha-Tocopherol/metabolism , gamma-Tocopherol/metabolism , Gene Expression Regulation, Plant/genetics , Gene Expression Regulation, Plant/physiology , Promoter Regions, Genetic/genetics
5.
3 Biotech ; 8(8): 325, 2018 Aug.
Article in English | MEDLINE | ID: mdl-30034989

ABSTRACT

γ-Tocopherol methyl transferase (γ-TMT) (EC 2.1.1.95) is the key enzyme of the tocopherol biosynthetic pathway that determines the α-tocopherol concentration in plants. The overexpression of γ-TMT has been a successful approach for α-tocopherol enrichment of most plants including soybean. The typical soybean varieties are rich in γ-tocopherol (constitutes nearly 65-70% of its total seed tocopherol pool), while α-tocopherol, the biologically most active form among all tocopherols, constitutes only 10% of the total tocopherol content. The identification of soybean varieties that have seed α-tocopherol as high as > 20% of the total tocopherols has shifted attention towards the breeding based approach for α-tocopherol enrichment of this crop. Previous research on this aspect suggests that polymorphisms in γ-TMT promoter might be associated with the high α-tocopherol concentration of some soybean varieties. To understand the molecular basis of genetic variation for α-tocopherol concentration in Indian varieties of soybean we cloned the 1.4 kb upstream promoter region of γ-TMT from a high α-tocopherol containing soybean variety (Bragg) as well as from a low α-tocopherol containing variety (DS 2706). Cloning of each of these promoters in pORE R2 vector having GUS reporter gene and the subsequent GUS assay revealed a slightly high promoter activity of Bragg γ-TMT as compared to DS 2706 γ-TMT. On promoter sequence analysis, no sequence polymorphisms were observed in the core promoter region of this gene. However, seven single nucleotide polymorphisms (SNPs) were observed outside the core promoter region. Further study based on deletion construct analysis of this promoter will elucidate the significance of these SNPs in influencing the activity of γ-TMT promoter and the α-tocopherol concentration.

6.
J Agric Food Chem ; 65(50): 11054-11064, 2017 Dec 20.
Article in English | MEDLINE | ID: mdl-29121768

ABSTRACT

Tocopherols composed of four isoforms (α, ß, 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.


Subject(s)
Glycine max/genetics , Plant Proteins/genetics , Tocopherols/metabolism , Transcription, Genetic , Biosynthetic Pathways , Gene Expression Regulation, Plant , Genotype , Oxidoreductases/genetics , Oxidoreductases/metabolism , Plant Proteins/metabolism , Prephenate Dehydrogenase/genetics , Prephenate Dehydrogenase/metabolism , Seeds/chemistry , Seeds/enzymology , Seeds/genetics , Seeds/metabolism , Glycine max/chemistry , Glycine max/enzymology , Glycine max/metabolism , Tocopherols/chemistry , Transferases/genetics , Transferases/metabolism , Tyrosine Transaminase/genetics , Tyrosine Transaminase/metabolism
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