Abstract:In this study, 7 TkAPXs genes were identified in Taraxacum koksaghyz whole genome using bioinformatic methods. Further analysis revealed that 2 genes (TkAPX4/TkAPX6) were replication genes. According to the results of phylogenetic relationships, 7 TkAPX genes were divided into four groups. The chromosomal localization analysis indicated that the 7 TkAPX genes were widely distributed and located on 7 different chromosomes. Subcellular localization results indicated that TkAPX1, TkAPX3, TkAPX5 and TkAPX7 were localized in the cytoplasm, TkAPX4 and TkAPX6 were localized on the plasma membrane, and TkAPX2 was localized in the chloroplast. The analysis of the cisacting element in the promoter region shows that there are a large number of stress response elements in TkAPXs sequence, suggesting that there might be sensitive stress response of TkAPXs to various external stress. Realtime quantitative PCR analysis showed that the expression levels of 7 TkAPX genes family members in calyxes, petals and pedicels were low. The expression level of most TkAPXs in roots and leaves was greater than that of flowers and latex. TkAPX1 has the highest expression level in roots and stems, suggesting that it may play an important role in the growth and development of T. koksaghyz. Furthermore, we detected the expression level of TkAPX genes after stress (cold, hot, salt, drought) and hormone (ethylene, methyl jasmonate) treatments. The expression levels of TkAPX3 in roots and leaves increased significantly compared with the control indicated that TkAPX3 may be involved in the stress response and hormone response in T. koksaghyz.