Browsing by Author "Sushmita"

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Failure of methanol detoxification in pests confers broad spectrum insect resistance in PME overexpressing transgenic cotton
(Elsevier Ireland Ltd, 2023) Alka Srivastava; Gourav Jain; Sushmita; Sateesh Chandra; Vinay Kalia; Santosh Kumar Upadhyay; Rama Shanker Dubey; Praveen Chandra Verma
Methanol is noxious to insect pests, but most plants do not make enough of it to shield themselves from encroaching insects. Methanol emission is known to increase in the instance of herbivory. In the current study, we showed that Aspergillus niger pectin methylesterase over-expression increases methanol emission and confers resistance to polyphagous insect pests on transgenic cotton plants by impeding the possible methanol detoxification pathways. Transgenic plants emitted ∼11 fold higher methanol displaying insect mortality of 96% and 93% in Helicoverpa armigera and Spodoptera litura, respectively. The larvae were unable to survive and finish their life cycle and the surviving larvae exhibited severe growth retardation. Insects try to detoxify methanol via catalase, carboxylesterase and cytochrome P450 monooxygenase enzymes, amongst which cytochrome P450 plays a major role in oxidizing methanol to formaldehyde and formaldehyde to formic acid, which is broken down into carbon dioxide and water. In our study, catalase and esterase enzymes were found to be upregulated, but cytochrome P450 monooxygenase levels were not much affected. Leaf disc assays and In-planta bioassays also showed 50–60% population reduction in the sap sucking pests, such as Bemisia tabaci and Phenacoccus solenopsis. These findings imply that elevated methanol emissions confer resistance in plants against chewing and sap-sucking pests by tampering the methanol detoxification pathways. Such mechanism will be useful in imparting expansive resistance against pests in plants. © 2023 Elsevier B.V.
Identification and characterization of pectin remodeling gene families in Withania somnifera and their interaction during biotic stress
(Elsevier B.V., 2023) Gourav Jain; Yogeshwar Vikram Dhar; Alka Srivastava; Manisha Singh; Sushmita; Sanchita Singh; Ankit Saxena; Sanjeev K. Shukla; Ratnasekhar Ch; Mehar Hasan Asif; Veena Pande; Praveen Chandra Verma
The Pectin methylesterase (PME), Pectin methylesterase inhibitor (PMEI), and Subtilase (SBT) are pectin remodeling enzymes that play an important role in plant growth and development as well as response to various biotic and abiotic stress conditions. Withania somnifera is an important medicinal plant that gained attention for its phytochemical properties, but relatively little in-depth genomic exploration has been available, including PME, PMEI, and SBT genes. In the present study, 54 PMEs, 19 PMEIs, and 51 SBTs genes were identified from the W. somnifera transcriptome. A detailed phylogeny was performed, followed by a conserved sequence signature analysis, which revealed the major phylogenetic division with Solanum lycopersicum. Insect infestation can cause a significant increase in the functions of these genes, which were identified using PME activity, methanol content, and emission, often by several orders of magnitude. WsPME28, WsPME32, and WsPME50 are putative genes that are significantly upregulated up to six fold during insect infestation, according to gene expression profile analysis. To study specific relative interactions for a PME-SBT pair, molecular docking analysis was performed and found that the serine residue of WsSBT37 interacts with the processing motif (RKLL) of WsPME28 and releases mature PME. As per our best knowledge, this is the first investigation into the identification and characterization of the PME, PMEI, and SBT gene families in W. somnifera. This study will lay the groundwork for future studies targeting these genes, thus giving a better understanding of the stress tolerance mechanism in W. somnifera, and will serve as a reference for determining the most specific SBT-PME pairs in development and stress conditions. © 2023 Elsevier B.V.