In this study,different disease-resistant inbred lines of maize,Mo17 (high),Zheng58 (medium),Ji419 (low),were inoculated with the pathogen spore of southern leaf blight,C.heterostrophus,for 0,6,12,24,36 and 48 hours.Through semi-quantitative and real-time PCR technology,the expression patterns of some key genes were explored in response to pathogen infection,including TPS6 and TPS11 for sesquiterpenoid phytoalexin Zealexin biosynthesis,An2 for diterpenoid phytoalexin Kauralexin biosynthesis,and AOC,the key gene of jasmonic acid (JA) metabolism.The results were followed:TPS6 and TPS11 gene expression in Mo17 were not induced significantly while the gene accumulation of An2 increased rapidly after inoculation.In the mean time,AOC gene expression was significantly increased after inoculation for 12 h in Mo17.TPS6 and TPS11 gene expression in Zheng58 increased rapidly,and reached the highest at 24 h.The An2 gene expression gradually increased,but the difference was not significant.The AOC gene expression increased significantly after inoculation for 6 h.The TPS6,TPS11 and An2 of Ji419 were upregulated in 24 h,slower than that in other two lines,and AOC gene expression showed a decreasing trend in the early phase and reached the highest levels at 24 h and 48 h.These results indicated that two types of terpenoid phytoalexins exhibited different metabolic response temporally in response to C.heterostrophus inoculation,but both were mediated with JA signal.The defense response mediated by metabolism of terpenoid phytoalexin was faster in resistant inbred line than that in the susceptible one,which is consistent with their resistance difference.Investigation of the defense response for terpenes phytoalexin metabolic genes provided an important theoretical basis for clarifying the defense mechanisms of maize varieties with different resistance against southern leaf blight.