Browsing by Author "Bansal, Sakshi"

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Heavy metal stress in rice: uptake, transport, signaling and tolerance mechanisms
(John Wiley & Sons, 2021) Kaur, Ravneet; Das, Susmita; Bansal, Sakshi; Singh, Gurbir; Sardar, Shaswati; Dhar, Hena; Ram, Hasthi
Heavy metal contamination of agricultural fields has become a global concern as it causes a direct impact on human health. Rice is the major food crop for almost half of the world population and is grown under diverse environmental conditions, including heavy metal-contaminated soil. In recent years, the impact of heavy metal contamination on rice yield and grain quality has been shown through multiple approaches. In this review article, different aspects of heavy metal stress, i.e. uptake, transport, signalling and tolerance mechanisms, are comprehensively discussed with special emphasis on rice. For uptake, some of the transporters have specificity to one or two metal ions, whereas many other transporters are able to transport many different ions. After uptake, the intercellular signalling is mediated through different signaling pathways involving the regulation of various hormones, alteration of calcium levels and the activation of Mitogen-Activated Protein kinases. Heavy metal stress signals from various intermediate molecules activate various transcription factors, which triggers the expression of various antioxidant enzymes. Activated antioxidant enzymes then scavenge various reactive oxygen species, which eventually leads to stress tolerance in plants. Non-enzymatic antioxidants, such as ascorbate, metalloids and even metal-binding peptides (metallothionein and phytochelatin) can also help to reduce metal toxicity in plants. Genetic engineering has been successfully used in rice and many other crops to increase metal tolerance and reduce heavy metals accumulation. A comprehensive understanding of uptake, transport, signalling and tolerance mechanisms will help to grow rice plants in agricultural fields with less heavy metal accumulation in grains.
Identification and molecular characterization of rice bran-specific lipases
(Springer Nature Publishing AG, 2021) Bansal, Sakshi; Sardar, Shaswati; Sinha, Kshitija; Bhunia, Rupam Kumar; Katoch, Megha; Sonah, Humira; Deshmukh, Rupesh; Ram, Hasthi
Key message Among the 113 lipases present in rice genome, bran and endosperm-specifc lipases were identifed and lipase activity for one of the selected lipase gene is demonstrated in yeast. Abstract: Rice bran is nutritionally superior than endosperm as it has major reservoirs of various minerals, vitamins, essential mineral oils and other bioactive compounds, however it is often under-utilized as a food product due to bran instability after milling. Various hydrolytic enzymes, such as lipases, present in bran causes degradation of the lipids present and are responsible for the bran instability. Here, in this study, we have systematically analyzed the 113 lipase genes present in rice genome, and identifed 21 seed-specifc lipases. By analyzing the expression of these genes in diferent seed tissues during seed development, we have identifed three bran-specifc and three endosperm-specifc lipases, and one lipase which expresses in both bran and endosperm tissues. Further analysis of these genes during seed maturation and seed germination revealed that their expression increases during seed maturation and decreases during seed germination. Finally, we have shown the lipase activity for one of the selected genes, LOC_Os05g30900, in heterologous system yeast. The bran-specifc lipases identifed in this study would be very valuable for engineering designer rice varieties having increased bran stability in post-milling.
Reference gene identification for gene expression analysis in rice under different metal stress
(Elsevier B.V., 2021) Soni, Praveen; Shivhare, Radha; Kaur, Amandeep; Bansal, Sakshi; Sonah, Humira; Deshmukh, Rupesh; Giri, Jitender; Lata, Charu; Ram, Hasthi
Real-time quantitative polymerase chain reaction (RT-qPCR) is the most common approach to quantify changes in gene expression. Appropriate internal reference genes are essential for normalization of data of RT-qPCR. In the present study, we identified suitable reference genes for gene expression analysis in rice seedlings subjected to different heavy metal stresses such as deficiencies of iron and zinc and toxicities of cobalt, cadmium and nickel. First, from publically available RNA-Seq data we identified 10 candidate genes having stable expression. We also included commonly used house-keeping gene OsUBQ5 (Ubiquitin 5) in our analysis. Expression stability of all the 11 genes was determined by two independent tools, NormFinder and geNorm. Our results show that selected candidate reference genes have higher stability in their expression compared to that of OsUBQ5. Genes with locus ID LOC_Os03g16690, encoding an oxysterol-binding protein (OsOBP) and LOC_Os01g56580, encoding Casein Kinase_1a.3 (OsCK1a.3) were identified to be the most stably expressed reference genes under most of the conditions tested. Finally, the study reveals that it is better to use a specific reference gene for a specific heavy metal stress condition rather than using a common reference gene for multiple heavy metal stress conditions. The reference genes identified here would be very useful for gene expression studies under heavy metal stresses in rice.
Rice lipases: a conundrum in rice bran stabilization: a review on their impact and biotechnological interventions
(Springer Nature Publishing AG, 2023) Bansal, Sakshi; Sundararajan, Sathish; Shekhawat, Pooja Kanwar; Singh, Shivangi; Soni, Praveen; Tripathy, Manas K.; Ram, Hasthi
Rice is a primary food and is one of the most important constituents of diets all around the world. Rice bran is a valuable component of rice, containing many oil-soluble vitamins, minerals, and oil. It is known for its ability to improve the economic value of rice. Further, it contains substantial quantities of minerals like potassium, calcium, magnesium, iron and antioxidants like tocopherols, tocotrienols, and γ-oryzanol, indicating that rice bran can be utilized efectively against several life-threatening disorders. It is difcult to fully utilize the necessary nutrients due to the presence of lipases in rice bran. These lipases break down lipids, specifcally Triacylglycerol, into free fatty acids and glycerol. This review discusses physicochemical properties, mechanism of action, distribution, and activity of lipases in various components of rice seeds. The phylogenetic and gene expression analysis helped to understand the diferential expression pattern of lipase genes at diferent growth phases of rice plant. Further, this review discusses various genetic and biotechnological approaches to decrease lipase activity in rice and other plants, which could potentially prevent the degradation of bran oil. The goal is to establish whether lipases are a major contributor to this issue and to develop rice varieties with improved bran stability. This information sets the stage for upcoming molecular research in this area.