Sweetpotato (Ipomoea batatas L.) is a globally important food crop that is susceptible to infestation with the root-knot nematode, Meloidogyne incognita, which causes substantial crop losses. Previous transcriptomic and proteomic analyses identified several genes that displayed differential expression patterns in susceptible and resistant cultivars in response to root-knot nematode (RKN) infection. As a result of previous study, RKN infection was confirmed in the RKN-susceptible sweetpotato cultivar Yulmi. Transcriptome analysis confirmed that among the genes that respond in this process, there are many genes related to ethylene biosynthesis. Therefore, in this study, we focused on the ACC oxidase (ACO) gene, the final enzyme of ethylene biosynthesis, and analyzed the expression patterns under various abiotic stress conditions. Using transcriptome data from our previous study, various expression changes in the four ACO genes used in this study were confirmed during RKN infection. The expression of G25011|TU41034 decreased during RKN infection compared to the untreated control, while the expression of G31097|TU51009, G28360|TU46486, and G15447|TU25395 genes increased in the early stages of RKN infection. Expressions of four ACO genes in leaves of sweetpoato were investigated under abiotic stress conditions such as wounding, high salinity, dehydration, and low temperature stress treatment. Expression of the G25011|TU41034 was significantly increased under abiotic stress conditions except low temperature. G31097|TU51009 was hardly expressed under abiotic stress conditions. Although the expression pattern of G28360|TU46486 and G15447|TU25395 was slightly different depending on the type of abiotic stress, an overall increase in expression was observed. It is expected that this study will be used as basic data on how ethylene biosynthesis responds not only to nematode infection but also to various abiotic stress conditions and will be helpful in functional studies of various crops.