Identification and characterization of pectin remodeling gene families in Withania somnifera and their interaction during biotic stress

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.