Spermidine hydroxycinnamoyltransferase genes (OsSHT) participate in herbivory-stress memory and confer resistance against Spodoptera frugiperda in Oryza sativa

Plants possess an extraordinary capacity to perceive and memorize environmental stimuli, which allows them to respond to subsequent challenges with more robust and/or faster responses, known as priming. There is limited information on specific priming genes or herbivory memory genes, and the phenomenon has been rarely studied in rice plants. We were using transcriptome analysis, metabolic profiling, and genetic analysis, and combining them with in vivo or in vitro caterpillar performance experiments to address this issue. Our study suggested that prior infestation of rice plants by fall armyworm (FAW) larvae led to a moderate improvement in defense against subsequent infestations and OsSHT1 and OsSHT2 were identified as potential memory-related genes through transcriptome analysis of main crop and ratoon rice treatment experiments. Upon infestation by FAW larvae, the expression levels of OsSHT1 and OsSHT2 were upregulated, leading to spermidine-based phenolamines (spd-PAs) accumulation in primed plants.