Silicon-mediated resistance to Spodoptera frugiperda in rice modulates growth and defense processes via transcriptional reprogramming

Authors: SHARMA, JYOTI - Louisiana State University Agcenter; CHAUDHARY, CHANDER KANT - Louisiana State University Agcenter; PRUTHI, RAJAT - Oregon State University; KONDI, RAVI - Louisiana State University Agcenter; Gaffke, Alexander; SUDBUDHI, PRASANTA - Louisiana State University Agcenter; Tai, Thomas; STOUT, MICHAEL - Louisiana State University Agcenter

Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/15/2026
Publication Date: 9/1/2026
Citation: Sharma, J., Chaudhary, C.K., Pruthi, R., Kondi, R.K.R., Gaffke, A.M., Sudbudhi, P.K., Tai, T., Stout, M.J. 2026. Silicon-mediated resistance to Spodoptera frugiperda in rice modulates growth and defense processes via transcriptional reprogramming. Plant and Soil. https://doi.org/10.1007/s11104-026-09012-6.
DOI: https://doi.org/10.1007/s11104-026-09012-6

Interpretive Summary: The rice gene OsLsi1 encodes a transporter localized to rice roots, which is responsible for the uptake of silicon into rice roots for subsequent distribution throughout the plant. Three rice OsLsi1 mutant lines exhibiting different levels of silicon were used in this study to examine the role of silicon accumulation on defense-related pathways and rice gene expression in response to a common insect pest, the fall armyworm. Analysis of jasmonic acid, a plant hormone involved in defense signaling in plants, revealed a significant increase in this hormone in response to fall armyworm feeding on the rice leaves irrespective of silicon content. Gene expression analysis using the RNA-seq technique showed that insect feeding also affected gene expression in both the mutant lines and the normal (wild-type) rice plants. Among the genes showing differences in expression were genes encoding transcription factors, which is consistent with a regulatory role in silicon-mediated plant defenses. Other genes showing differences in expression under armyworm feeding were those associated with plant hormone metabolism and stress responses. Rice lines with higher silicon content displayed increased expression of genes related to insect recognition. Insights into the role of silicon in increasing resistance to insects may contribute to new pest protection approaches.

Technical Abstract: Silicon (Si) is known to confer resistance in plants against abiotic and biotic stresses; however, questions remain about the underlying mechanisms of Si-mediated resistance against insect herbivores. We investigated the Si-mediated resistance mechanisms in rice against fall armyworm (FAW) Spodoptera frugiperda using OsLsi1 mutant rice (cv. Nipponbare) lines, deficient in Si uptake from the soil. We investigated these questions using a multidisciplinary approach combining bioassays of insects and plant growth, biochemical quantification of defense metabolites, phytohormones, volatiles, whole genome sequencing, and transcriptomics. Si played a key role in mediating constitutive resistance to FAW, but Si content did not substantially alter induced responses. High Si content promoted compensatory growth post-herbivory and had no effect on constitutive or induced activities of peroxidases, polyphenol oxidases, trypsin inhibitors, and jasmonic acid. Low Si plants constitutively emitted higher levels of certain terpene volatiles. Comparative transcriptomics across wild-type and mutant lines showed that Si modulates gene expression under both constitutive and post-herbivory. Plants with high Si levels appear well defended but also capable of allocating more resources to re-growth than low Si plants. Genes including OsbHLH024, OsLsi1, OsMSH3, OsARC5, OsCKX2, and OsBBX3 are candidates for engineering rice varieties with enhanced herbivory resistance.