Amardeep Singh Virdi

Abiotic stress responses in plants: roles of calmodulin-regulated proteins

Intracellular changes in calcium ions (Ca2+) in response to different biotic and abiotic stimuli are detected by various sensor proteins in the plant cell. Calmodulin (CaM) is one of the most extensively studied Ca2+-sensing proteins and has been shown to be involved in transduction of Ca2+ signals. After interacting with Ca2+, CaM undergoes conformational change and influences the activities of a diverse range of CaM-binding proteins. A number of CaM-binding proteins have also been implicated in stress responses in plants, highlighting the central role played by CaM in adaptation to adverse environmental conditions. Stress adaptation in plants is a highly complex and multigenic response. Identification and characterization of CaM-modulated proteins in relation to different abiotic stresses could, therefore, prove to be essential for a deeper understanding of the molecular mechanisms involved in abiotic stress tolerance in plants. Various studies have revealed involvement of CaM in regulation of metal ions uptake, generation of reactive oxygen species and modulation of transcription factors such as CAMTA3, GTL1, and WRKY39. Activities of several kinases and phosphatases have also been shown to be modulated by CaM, thus providing further versatility to stress-associated signal transduction pathways. The results obtained from contemporary studies are consistent with the proposed role of CaM as an integrator of different stress signaling pathways, which allows plants to maintain homeostasis between different cellular processes. In this review, we have attempted to present the current state of understanding of the role of CaM in modulating different stress-regulated proteins and its implications in augmenting abiotic stress tolerance in plants.

Diversity in quality traits amongst Indian wheat varieties I: flour and protein characteristics.

The relationships of polymeric as well as monomeric proteins (unextractable and extractable) with various flour properties amongst Indian wheat varieties were evaluated. Unextractable polymeric proteins and unextractable monomeric proteins in flours ranged from 23.83% to 51.97% and 48.03% to 76.17%, respectively. Varieties with higher grain hardness index resulted into flours with higher a(∗), ash content and protein content. Unextractable polymeric and monomeric proteins were related to grain hardness index. Unextractable polymeric proteins showed a positive correlation with gluten index and LASRC. Majority of varieties with HMW-GS combinations of 91kDa+80kDa+78kDa+74kDa PPs showed very high grain hardness index (97-100).

Influence of Early and Delayed Transplantation of Paddy on Physicochemical, Pasting, Cooking, Textural, and Protein Characteristics of Milled Rice

ABSTRACT Milled rice of four indica cultivars (PR114, PR116, PR118, and PAU201) obtained from early (June 5 and 15) and delayed (June 25 and July 5) transplanted paddy was evaluated for physicochemical, pasting, cooking, and protein characteristics. During the grain-filling and development stage, early transplanted paddy experienced average maximum and minimum temperatures of 32.8 and 22.3°C, respectively, against 30.8 and 15°C, respectively, for delayed transplanted paddy. Lightness (L*) value, protein content, and lipid content of milled rice were lower, whereas apparent amylose content, cooked grain hardness, final viscosity, and setback viscosity were higher in the delayed transplanted paddy. Whiteness of milled rice of PR114, PR116, and PR118 from delayed transplanted paddy was lower than milled rice from early transplanted paddy. PAU201 did not show any change in whiteness with delayed transplantation. Cooked rice of PAU201 showed exceptionally higher adhesiveness and lower hardness compared with ot...

A sorghum 85 kDa heat stress-modulated protein shows calmodulin-binding properties and cross-reactivity to anti-Neurospora crassa Hsp 80 antibodies

The present study, carried out to identify stress‐modulated calmodulin (CaM)‐binding proteins in sorghum, resulted in the isolation of several proteins, which showed binding to CaM‐Sepharose matrix. Calmodulin gel overlay assay and MALDI‐ToF MS analysis revealed that an 85 kDa protein (Hsp85), which interacted with calmodulin, cross‐reacted with anti‐N. crassa Hsp80 antibodies. Since these antibodies bind to plant Hsp90, sorghum Hsp85 is likely to be a member of the Hsp90 family. This study provides the first evidence that a member of Hsp90 (Hsp85) in plants exhibits CaM‐binding properties.

Effect of canning on color, protein and phenolic profile of grains from kidney bean, field pea and chickpea

The aim of the present study was to evaluate the effect of canning on color, protein and phenolic profile of grains of kidney bean, field pea and chickpea varieties/accession. Color of grains of different pulses was enhanced after canning. Grains L* (lightness) decreased while a* (redness to yellowness) and b* (greenness to blueness) increased after canning in all the pulses. Protein profiling of grains of different pulses after canning revealed that kidney bean and chickpea, respectively, had the least and the most thermally susceptible polypeptides. Kidney bean and chickpea showed higher Percentage washed drained weight (PWDW) than field pea. Pulse with more grain hardness and PWDW showed higher degree of grain splitting during canning. Grain splitting was also higher in dark colored accessions/varieties as compared to the light colored. Ferulic acid was the most predominant compound present in raw grains of different pulses. Raw kidney bean grains showed higher accumulation of catechin, chlorogenic, protocatechuic acid, p-coumaric acid and ferulic acid than those of chickpea and field pea. Canning caused reduction in all the phenolic compounds except gallic acid and most prominent effect of canning on protocatechuic acid, chlorogenic and ferulic acid was observed.

Comparison of Composition, Protein, Pasting, and Phenolic Compounds of Brown Rice and Germinated Brown Rice from Different Cultivars

Physical characteristics, amino acids composition, protein profiling, pasting characteristics, and phenolic compounds of brown rice (BR) and germinated brown rice (GBR) from different paddy cultivars (PB1, PS44, PB1509, PB1121, and PS5) were investigated. L* (lightness) decreased, but a* (redness and greenness) and b* (yellowness and blueness) increased with germination. Protein and ash content increased, whereas fat and amylose contents decreased with germination. GBR showed lower hardness and gumminess than BR. Foam stability and water absorption capacity from GBR flour were higher compared with BR flour. Accumulation of γ-aminobutyric acid, histidine, arginine, proline, methionine, and acidic amino acids increased significantly with germination, and increase was related to change in accumulation of glutelin and prolamins. The accumulation of prolamins and glutelin acidic and basic subunits decreased with germination. GBR flour showed lower pasting viscosities compared with BR flour. Ferulic acid, p-cou...

A novel method for whole blood PCR without pretreatment

PCR is usually performed on purified DNA. However, the extraction of DNA from whole blood is time consuming and involves the risk of contamination at every step. Hence, it is desirable to amplify DNA directly from whole blood. Earlier, investigators tried to achieve this target by either pretreatment of whole blood samples with different agents or by altering the conventional thermal cyclic conditions. This would make the technique cumbersome and time consuming. Here, we describe a simple protocol to amplify DNA directly from whole blood without the need of pretreatment. PCR buffer system was optimized in the laboratory and Apolipoprotein B gene was used as a model for this experiment. 480 bp was the target site for amplification. Fresh whole blood samples were used both from healthy and diseased individuals (coronary artery disease patients). Successful amplification was achieved with 1 μl volume of whole blood and it was comparable to that of genomic DNA. No pretreatment of whole blood samples was required with the optimized buffer system. 3mM concentration of MgCl(2) was observed to be optimal and hence used in the reaction mixture. Amplification was relatively better with this buffer system as compared to that of commercially available PCR buffer. With the present technique, amplicon detection did not require the centrifugation/dilution of the PCR products which further saves time. Successful amplification was achieved in both the healthy and diseased blood samples, indicating the robustness of the technique as changed blood composition and presence of increased inhibitory molecules in the diseased state did not seem to affect the efficacy of the present technique. In conclusion, as compared to the existing protocols for whole blood PCR, the present technique is relatively novel, simple, requires minimal steps and eliminates the need for additional standardizations.

Evidence for the possible involvement of calmodulin in regulation of steady state levels of Hsp90 family members (Hsp87 and Hsp85) in response to heat shock in sorghum

Pharmacological studies, using Ca2+ channel blockers (LaCl3 and verapamil) and calmodulin (CaM) antagonists (CPZ and W7), were carried out to understand the role of Ca2+/CaM in the regulation of heat shock-induced expression of Hsp90 (Hsp87 and Hsp85) and Hsp70 (Hsp75 and Hsp73) members in sorghum. It was observed that the expression of both Hsp87 and Hsp85 proteins was decreased in presence of Ca2+ channel blockers and CaM antagonists, under both control and heat stress conditions, as contrary to the steady state levels of Hsp75 and Hsp73, which were not affected significantly under similar conditions. Further, the exposure of sorghum seedlings to geldanamycin, a specific inhibitor of Hsp90, resulted in induction of Hsp87 and Hsp85 in the absence of heat shock also. This study provides the first evidence suggesting that in plants, the in vivo expression of Hsp90 (Hsp87 and Hsp85) is likely to be modulated by Ca2+/CaM under normal and thermal stress conditions. The likely implications of these findings are discussed.

Successive Reduction Dry Milling of Normal and Waxy Corn: Grain, Grit, and Flour Properties

Dry milling of different corn types resulted in varied proportions of germ, pericarp, grit and flour. Grit and flour produced during different reduction stages varied in particle size and chemical constituents, hence applications in food industry. In this study, recovery of different fractions and variation in physicochemical and pasting properties of grit and flour fractions obtained during 3 successive reduction dry millings of 2 normal (African tall, HQPM1) and 1 waxy corn (IC 550353) were evaluated. Waxy corn grains had the highest L*, a*, b*, ash, fat, and protein content and the lowest weight. Waxy and African tall gave the highest recovery of germ and pericarp, respectively. Waxy corn showed lower grit and flour recovery as compared to normal corn. Flour fractions showed higher L* and lower a* and b* values than grit fractions. Particle size of grit and flour fractions ranged from 840 to 982 μm and 330 to 409 μm, respectively. Fractions with larger particle size showed lower L* value. The b* value showed positive correlation with yellow pigment content. Grit and flour from the 1st reduction stage showed higher ash and fat content. Protein content was correlated positively with ash content and negatively with L* value. Grit and flour fractions with higher protein content had lower pasting viscosities. Pasting viscosities were higher for flours than their corresponding grits. Protein profiling of grit and flour fractions from different stages showed quantitative and qualitative differences in medium (22, 28, and 35 kDa) and low molecular weight (16, 17, and 19 kDa) polypeptides and were related to grit and flour yield.

Quality traits analysis and protein profiling of field pea (Pisum sativum) germplasm from Himalayan region.

The grain and flour characteristics of different field pea (FP) accessions were evaluated. Accessions with higher grain weight had less compact structure with a greater proportion of large-sized starch granules. Accessions with higher protein content had lower starch content, blue value and λ(max) whereas accessions with higher amylose showed higher resistant starch (RS) and final viscosity and lower rapidly digestible starch (RDS). Ca, Zn, K and Fe content vary significantly amongst different accessions and creamish green and white seeds accessions showed higher Fe and Zn content. Yellow coloured accessions (1.36-3.71%) showed lower antioxidant activity as compared to brownish and green coloured accessions (4.06-9.30%). Out of 21 major polypeptides observed (9-100 kDa), 11 showed differential trypsin inhibitory activity (TIA) under non-reducing conditions. Polypeptides of 68, 46, 33 and 22 kDa showed prominent TIA.