Browsing by Author "Shekhar, Shubhendu"

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Carboxylate clamp tetratricopeptide repeat (TPR) domain containing Hsp90 cochaperones in Triticeace: an insight into structural and functional diversification
(Elsevier B.V., 2018) Mishra, Divya; Shekhar, Shubhendu; Chakraborty, Subhra; Chakraborty, Niranjan
The molecular chaperones serve as surveillance molecules that mediates regulatory crosstalk between protein folding and degradation pathways under natural and stress conditions. In present study, we focused on the diversification and role of tetratricopeptide repeat (TPR) domain containing Hsp90 cochaperones. These cochaperone were recognized by the presence of three motifs of TPR with the basic conserved residues often referred to as carboxylate clamp (CC). A total of 213 putative CC-TPRs were found in Triticeace, clustered into 16 groups, amongst which few CC-TPR families such as TPR-RPAP3 and TPR-SMYD were documented. Domain architecture and genomic organization revealed that CC-TPRs are very diverse in nature. Evolutionary analyses showed that CC-TPRs are conserved, stable and ubiquitous in nature. Analysis of available RNA-seq data revealed a high degree of tissue-specific expression of 1-TPR and TaTPR-FKBP family members at various developmental stages. The transcripts of TaCC-TPRs displayed differential expression in two contrasting wheat cultivars under abiotic stress conditions. Complementation and heterologous expression of TaTPR-FKBP5 in yeast conferred abiotic stress tolerance. Together, these results provide a glimpse into the genetic diversity and evolution of CC-TPRs in Triticeace, which would help to better understand of how TPR-domain cochaperones function in plants.
Characterization of the nuclear proteome of a dehydration-sensitive cultivar of chickpea and comparative proteomic analysis with a tolerant cultivar
(John Wiley & Sons Ltd, 2013) Subba, Pratigya; Kumar, Rajiv; Gayali, Saurabh; Shekhar, Shubhendu; Parveen, Shaista; Pandey, Aarti; Datta, Asis; Chakraborty, Subhra; Chakraborty, Niranjan
Water deficit or dehydration hampers plant growth and development, and shrinks harvest size of major crop species worldwide. Therefore, a better understanding of dehydration response is the key to decipher the regulatory mechanism of better adaptation. In recent years, nuclear proteomics has become an attractive area of research, particularly to study the role of nucleus in stress response. In this study, a proteome of dehydration-sensitive chickpea cultivar (ICCV-2) was generated from nuclei-enriched fractions. The LC-MS/MS analysis led to the identification of 75 differentially expressed proteins presumably associated with different metabolic and regulatory pathways. Nuclear localisation of three candidate proteins was validated by transient expression assay. The ICCV-2 proteome was then compared with that of JG-62, a tolerant cultivar. The differential proteomics and in silico analysis revealed cultivar-specific differential expression of many proteins involved in various cellular functions. The differential tolerance could be attributed to altered expression of many structural proteins and the proteins involved in stress adaptation, notably the ROS catabolising enzymes. Further, a comprehensive comparison on the abiotic stress-responsive nuclear proteome was performed using the datasets published thus far. These findings might expedite the functional determination of the dehydration-responsive proteins and their prioritisation as potential molecular targets for better adaptation.
Comparative analysis of phytochemicals and nutrient availability in two contrasting cultivars of sweet potato (Ipomoea batatas L.)
(Elsevier B.V., 2014) Shekhar, Shubhendu; Mishra, Divya; Buragohain, Alak Kumar; Chakraborty, Subhra; Chakraborty, Niranjan
Sweet potato ranks as the world's seventh most important food crop, and has major contribution to energy and phytochemical source of nutrition. To unravel the molecular basis for differential nutrient availability, and to exploit the natural genetic variation(s) of sweet potato, a series of physiochemical and proteomics experiment was conducted using two contrasting cultivars, an orange-fleshed sweet potato (OFSP) and a white-fleshed sweet potato (WFSP). Phytochemical screening revealed high percentage of carbohydrate, reducing sugar and phenolics in WFSP, whereas OFSP showed increased levels of total protein, flavonoids, anthocyanins, and carotenoids. The rate of starch and cellulose degradation was found to be less in OFSP during storage, indicating tight regulation of gene(s) responsible for starch-degradation. Comparative proteomics displayed a cultivar-dependent expression of proteins along with evolutionarily conserved proteins. These results suggest that cultivar-specific expression of proteins and/or their interacting partners might play a crucial role for nutrient acquisition in sweet potato.
Comparative proteomics reveals a role for seed storage protein, AmA1 in cellular growth, development and nutrient accumulation
(American Chemical Society, 2013) Agrawal, Lalit; Narula, Kanika; Basu, Swaraj; Shekhar, Shubhendu; Ghosh, Sudip; Datta, Asis; Chakraborty, Niranjan; Chakraborty, Subhra
Seed storage proteins are known to be utilized as carbon and nitrogen source for growing seedlings and thus are considered as potential candidates for nutritional improvement. However, their precise function remains unknown. We have earlier shown that ectopic expression of a seed storage protein, AmA1, leads to increase in protein besides high tuber yield in potato. To elucidate the AmA1-regulated molecular mechanism affecting increased protein synthesis, reserve accumulation, and enhanced growth, a comparative proteomics approach has been applied to tuber life-cycle between wild-type and AmA1 potato. The differential display of proteomes revealed 150 AmA1-responsive protein spots (ARPs) that change their intensities more than 2.5-fold. The LC-ESI-MS/MS analyses led to the identification of 80 ARPs presumably associated with cell differentiation, regulating diverse functions, viz., protein biogenesis and storage, bioenergy and metabolism, and cell signaling. Metabolome study indicated up-regulation of amino acids paralleling the proteomics analysis. To validate this, we focused our attention on anatomical study that showed differences in cell size in the cortex, premedullary zone and pith of the tuber, coinciding with AmA1 expression and localization. Further, we interrogated the proteome data using one-way analysis of variance, cluster, and partial correlation analysis that identified two significant protein modules and six small correlation groups centered around isoforms of cysteine protease inhibitor, actin, heat shock cognate protein 83 and 14-3-3, pointing toward AmA1-regulated overlapping processes of protein enhancement and cell growth perhaps through a common mechanism of function. A model network was constructed using the protein data sets, which aim to show how target proteins might work in coordinated fashion and attribute to increased protein synthesis and storage reserve accumulation in AmA1 tubers on one hand and organ development on the other.
Comparison of proteomic and metabolomic profiles of two contrasting ecotypes of sweetpotato (Ipomoea batata L)
(Elsevier B.V., 2016) Shekhar, Shubhendu; Mishra, Divya; Gayali, Saurabh; Buragohain, Alak Kumar; Chakraborty, Subhra; Chakraborty, Niranjan
Sweetpotato has long been acknowledged as a significant contributor of global caloric needs, which continues to be of remarkable economic value. It is an important staple and emergency food in many countries and its annual world production hovers to about 130 million tons. The tubers act as sink and compete for the available photoassimilates eventually leading to the acquisition of nutrients and phytochemicals. Differential display of genes or gene-products, and metabolites causes differences in nutritive value of closely related ecotypes. To better understand the molecular basis for differential nutrient availability and phytochemicals, and exploit the natural genetic variation(s), we aimed at developing proteometabolic profiles of two contrasting ecotypes of sweetpotato. Proteomic analyses led to the identification of 1541 and 1201 proteins in orange fleshed and white fleshed sweetpotato ecotypes, respectively, presumably associated with binding, followed by catalytic, transferase, hydrolase, kinase and transporter activities. Furthermore, metabolome profiling revealed 148 and 126 metabolites in cv. OFSP and WFSP, respectively. This study would provide a basis for future comparative proteometabolomic efforts for sweetpotato, in particular and tuber crops in general. The results would expand our understanding of the proteome as well as metabolome and give new insights into how ecotype-specific traits are developed.
Cultivar-specific high temperature stress responses in bread wheat (Triticum aestivum L.) associated with physicochemical traits and defense pathways
(Elsevier B.V., 2017) Mishra, Divya; Shekhar, Shubhendu; Agrawal, Lalit; Chakraborty, Subhra; Chakraborty, Niranjan
The increasing global temperature by 1°C is estimated to reduce the harvest index in a crop by 6%, and this would certainly have negative impact on overall plant metabolism. Wheat is one of the most important crops with global annual production of over 600million tonnes. We investigated an array of physicochemical and molecular indexes to unravel differential response of nine commercial wheat cultivars to high temperature stress (HTS). The reduced rate in relative water content, higher membrane stability, slow chlorophyll degradation and increased accumulation of proline and secondary metabolites ingrained higher thermotolerance in cv. Unnat Halna, among others. The altered expression of several stress-responsive genes, particularly the genes associated with photosynthesis, heat shock proteins and antioxidants impinge on the complexity of HTS-induced responses over different genetic backgrounds and connectivity of adaptive mechanisms. This may facilitate the targeted manipulation of metabolic routes in crops for agricultural and industrial exploitation.
Ectopic expression of amaranth seed storage albumin modulates photoassimilate transport and nutrient acquisition in sweetpotato
(Nature Publishing Group, 2016) Shekhar, Shubhendu; Agrawal, Lalit; Mishra, Divya; Buragohain, Alak Kumar; Unnikrishnan, Mullath; Mohan, Chokkappan; Chakraborty, Subhra; Chakraborty, Niranjan
Storage proteins in plants, because of high nutrient value, have been a subject of intensive investigation. These proteins are synthesized de novo in the cytoplasm and transported to the storage organelles where they serve as reservoir of energy and supplement of nitrogen during rapid growth and development. Sweetpotato is the seventh most important food crop worldwide, and has a significant contribution to the source of nutrition, albeit with low protein content. To determine the behaviour of seed storage proteins in non-native system, a seed albumin, AmA1, was overexpressed in sweetpotato with an additional aim of improving nutritional quality of tuber proteins. Introduction of AmA1 imparted an increase in protein and amino acid contents as well as the phytophenols. The proteometabolomics analysis revealed a rebalancing of the proteome, with no significant effects on the global metabolome profile of the transgenic tubers. Additionally, the slower degradation of starch and cellulose in transgenic tubers, led to increased post-harvest durability. Present study provides a new insight into the role of a seed storage protein in the modulation of photoassimilate movement and nutrient acquisition.
Genotype independent regeneration and agrobacterium-mediated genetic transformation of sweet potato (Ipomoea batatas L.)
(Bangladesh Association for Plant Tissue Culture and Biotechnology, 2013) Shekhar, Shubhendu; Agrawal, Lalit; Buragohain, Alak Kumar; Datta, Asis; Chakraborty, Subhra; Chakraborty, Niranjan
Development of an efficient genotype independent regeneration and genetic transformation system in sweet potato continues to be of great interest. Agrobacterium‐mediated genetic transformation protocol was established in two different cultivars of sweet potato using Agrobacterium strain EHA105 harbouring binary plasmid pBI121 containing GUS and nptII genes. The internodal stem segments from 30‐day‐old micropropogated plants were used as explant with different combinations of media and hormones. MS and LS media with various concentrations of growth regulators proved to be non‐responsive and the infecundity was severe with the addition of cytokinins. Nonetheless, MS with 2,4‐D and TDZ gave a good percentage of callusing but with low differentiation. In different concentrations of NAA, significant amount of callusing was observed but percentage of rooting remained low in both the genotypes. Gamborg’s B5 supplemented with NAA proved to be the most suitable media and hormone combination, which yielded shoot formation after 8 ‐ 10 weeks with a regenera‐ tion efficiency of 40 ‐ 70%. Stable integration of transgene was confirmed by PCR analysis. Furthermore, qRT‐PCR analysis was performed to assess the transcript accumulation in addition to the GUS enzymatic assay in the transgenic lines.
Heat shock proteins and abiotic stress tolerance in plants
(Springer Nature, 2018) Mishra, Divya; Shekhar, Shubhendu; Singh, Deepika; Chakraborty, Subhra; Chakraborty, Niranjan
Abiotic stresses restrict plant growth and development, and reduce harvest index of many crop species worldwide. Maintenance of native conformation of proteins and reducing the accumulation of non-native proteins are imperative for survival under stress conditions as such stresses frequently lead to protein aggregation causing metabolic dysfunction. Heat shock proteins (HSP) play a key role in conferring abiotic stress tolerance. Plants protect themselves from numerous stresses by inducing HSP, besides some stress-responsive proteins, suggesting analogous response mechanisms. A close association between the HSP and ROS also co-exists, indicating that plants have evolved to gain a higher degree of regulation over ROS toxicity and can use ROS as elicitor to induce HSP for better adaptations through activating an array of molecules. Therefore, unraveling the mechanisms of plant response against various stress and the role of HSP in acquired stress tolerance is utmost important to delineate their specific function as a part of stress-responsive module. The HSP have been well characterized in different crop species, albeit the knowledge about their correlation with genome sequence information as well as their functional plasticity is limited.
High temperature stress responses and wheat: Impacts and alleviation strategies
(Elsevier B.V., 2021) Mishra, Divya; Shekhar, Shubhendu; Chakraborty, Subhra; Chakraborty, Niranjan
Over the past century, the average surface temperature and recurrent heatwaves have been steadily rising, affecting the yield potential of most food crops including bread wheat, the second most important caloric source, but is particularly vulnerable to the impacts of elevated temperatures. Significantly, the past decade has witnessed tremendous advancements in multiomics approaches to extract the key regulators that influence the adaptive responses to high temperature stress (HTS). With the help of genetic engineering technologies, transgenic wheat plants have been developed showing resistance to HTS without hampering productivity. In this review, we described the effect of rising temperature at a global scale and the drastic impacts on crops, particularly on wheat production. Also, this review is focused on accomplishing a deeper understanding of the genetic and molecular basis of HTS responses of crop plants, wheat in particular along with current strategies and technologies to generate thermotolerant varieties. Collective strategy and identified thresholds of HTS tolerance and susceptibility will contribute to the value-added modelling of wheat growth and yield under predictable future climate conditions.
Next-generation protein-rich potato expressing the seed protein gene AmA1 is a result of proteome rebalancing in transgenic tuber
(Proceedings of the National Academy of Sciences of the United States of America, 2010) Chakraborty, Subhra; Chakraborty, Niranjan; Agrawal, Lalit; Ghosh, Sudip; Narula, Kanika; Shekhar, Shubhendu; Naik, Prakash S.; Pande, P.C.; Chakrborti, Swarup Kumar; Datta, Asis
Protein deficiency is the most crucial factor that affects physical growth and development and that increases morbidity and mortality especially in developing countries. Efforts have been made to improve protein quality and quantity in crop plants but with limited success. Here, we report the development of transgenic potatoes with enhanced nutritive value by tuber-specific expression of a seed protein, AmA1 (Amaranth Albumin 1), in seven genotypic backgrounds suitable for cultivation in different agro-climatic regions. Analyses of the transgenic tubers revealed up to 60% increase in total protein content. In addition, the concentrations of several essential amino acids were increased significantly in transgenic tubers, which are otherwise limited in potato. Moreover, the transgenics also exhibited enhanced photosynthetic activity with a concomitant increase in total biomass. These results are striking because this genetic manipulation also resulted in a moderate increase in tuber yield. The comparative protein profiling suggests that the proteome rebalancing might cause increased protein content in transgenic tubers. Furthermore, the data on field performance and safety evaluation indicate that the transgenic potatoes are suitable for commercial cultivation. In vitro and in vivo studies on experimental animals demonstrate that the transgenic tubers are also safe for human consumption. Altogether, these results emphasize that the expression of AmA1 is a potential strategy for the nutritional improvement of food crops.
Wheat 2-Cys peroxiredoxin plays a dual role in chlorophyll biosynthesis and adaptation to high temperature
(John Wiley & Sons, 2021) Mishra, Divya; Shekhar, Shubhendu; Chakraborty, Subhra; Chakraborty, Niranjan
The molecular mechanism of high temperature stress (HTS) response, in plants, has so far been investigated using transcriptomics, while the dynamics of HTS‐responsive proteome remain unexplored. We examined the adaptive responses of the resilient wheat cultivar ‘Unnat Halna’ and dissected the HTS‐responsive proteome landscape. This led to the identification of 55 HTS‐responsive proteins (HRPs), which are predominantly involved in metabolism and defense pathways. Interestingly, HRPs included a 2‐cysteine peroxiredoxin (2CP), designated Ta2CP, presumably involved in stress perception and adaptation. Complementation of Ta2CP in yeast and heterologous expression in Arabidopsis demonstrated its role in thermotolerance. Both Ta2CP silencing and overexpression inferred the involvement of Ta2CP in plant growth and chlorophyll biosynthesis. We demonstrated that Ta2CP interacts with protochlorophyllide reductase b, TaPORB. Reduced TaPORB expression was found in Ta2cp‐silenced plants, while upregulation was observed in Ta2CP‐overexpressed plants. Furthermore, the downregulation of Ta2CP in Taporb‐silenced plants and reduction of protochlorophyllide in Ta2cp‐silenced plants suggested the key role of Ta2CP in chlorophyll metabolism. Additionally, the transcript levels of AGPase1 and starch were increased in Ta2cp‐silenced plants. More significantly, HTS‐treated Ta2cp‐silenced plants showed adaptive responses despite increased reactive oxygen species and peroxide concentrations, which might help in rapid induction of high‐temperature acclimation.
Wheat TaNACα18 functions as a positive regulator of high-temperature adaptive responses and improves cell defense machinery
(John Wiley & Sons, 2024) Mishra, Divya; Shekhar, Shubhendu; Subba, Pratigya; Prasad, T S Keshava; Chakraborty, Subhra; Chakraborty, Niranjan
Global wheat production amounted to >780 MMT during 2022-2023 whose market size are valued at >$128 billion. Wheat is highly susceptible to high-temperature stress (HTS) throughout the life cycle and its yield declines 5-7% with the rise in each degree of temperature. Previously, we reported an array of HTS-response markers from a resilient wheat cv. Unnat Halna and described their putative role in heat acclimation. To complement our previous results and identify the key determinants of thermotolerance, here we examined the cytoplasmic proteome of a sensitive cv. PBW343. The HTS-triggered metabolite reprograming highlighted how proteostasis defects influence the formation of an integrated stress-adaptive response. The proteomic analysis identified several promising HTS-responsive proteins, including a NACα18 protein, designated TaNACα18, whose role in thermotolerance remains unknown. Dual localization of TaNACα18 suggests its crucial functions in the cytoplasm and nucleus. The homodimerization of TaNACα18 anticipated its function as a transcriptional coactivator. The complementation of TaNACα18 in yeast and overexpression in wheat demonstrated its role in thermotolerance across the kingdom. Altogether, our results suggest that TaNACα18 imparts tolerance through tight regulation of gene expression, cell wall remodeling and activation of cell defense responses.