Browsing by Author "Agrawal, Lalit"

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Comparative proteomics of tuber induction, development and maturation reveal the complexity of tuberization process in potato (Solanum tuberosum L.)
(American Chemical Society, 2008) Agrawal, Lalit; Chakraborty, Subhra; Jaiswal, Dinesh Kumar; Gupta, Sonika; Datta, Asis; Chakraborty, Niranjan
Tuberization in potato ( Solanum tuberosum L.) is a developmental process that serves a double function, as a storage organ and as a vegetative propagation system. It is a multistep, complex process and the underlying mechanisms governing these overlapping steps are not fully understood. To understand the molecular basis of tuberization in potato, a comparative proteomic approach has been applied to monitor differentially expressed proteins at different development stages using two-dimensional gel electrophoresis (2-DE). The differentially displayed proteomes revealed 219 protein spots that change their intensities more than 2.5-fold. The LC-ES-MS/MS analyses led to the identification of 97 differentially regulated proteins that include predicted and novel tuber-specific proteins. Nonhierarchical clustering revealed coexpression patterns of functionally similar proteins. The expression of reactive oxygen species catabolizing enzymes, viz., superoxide dismutase, ascorbate peroxidase and catalase, were induced by more than 2-fold indicating their possible role during the developmental transition from stolons into tubers. We demonstrate that nearly 100 proteins, some presumably associated with tuber cell differentiation, regulate diverse functions like protein biogenesis and storage, bioenergy and metabolism, and cell defense and rescue impinge on the complexity of tuber development in 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.
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.
Insights into genetic engineering of crop plants for improved protein and molecular mechanism of transgene function
(Institute of Biotechnology, Acharya NG Ranga Agricultural University, Rajendranagar, Hyderabad, India, 2011) Agrawal, Lalit; Sharma, Ajay; Narula, Kanika; Datta, Asis; Chakraborty, Niranjan; Chakraborty, Subhra
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.