Geographical variation in metabolites of red pepper ( <i>Capsicum annuum</i> L.) from Korean cultivation regions revealed by ¹ H NMR

Red pepper (Capsicum annuum L.) is an important crop in South Korea. The metabolite composition of plants is influenced by environmental factors such as soil and climate. However, the geographical effects remain unclear. This study examined red peppers from five regions of South Korea: Chilgok, Yeongwol, Jeju, Gochang, and Yeonggwang. Metabolites in pericarp and seed tissues were analyzed using1 H NMR-based metabolomics, and statistical analyses revealed region-associated clustering patterns with partial overlap (e.g. Chilgok and Yeongwol). Chilgok peppers contained elevated levels of γ-aminobutyric acid, glutamine, and capsaicinate, consistent with low soil fertility and heat stress, whereas Yeongwol peppers showed high fructose and trehalose levels under nutrient-rich and moderate conditions. Jeju peppers exhibited reduced sugar and amino acid content, likely due to volcanic ash soil with a high cation exchange capacity and rainfall-induced nutrient dilution. Gochang and Yeonggwang peppers displayed intermediate profiles, reflecting mild water stress or balanced growth conditions. Similar tissue-specific trends were observed in the seeds. Variable importance in projection (VIP) analysis indicated that sugars, amino acids, and capsaicinoids were the key discriminators of regional differences. Overall, this study highlights the influence of agro-environmental conditions on red pepper metabolism and provides insights into region-specific cultivation strategies.