Plants produce thousands of terpenoid compounds,many of them exhibit great benefits for human health.An approach based on the sequencing technologies derived from specific targeted plant cells has lead to the identification of key genes coding for enzymes involved in the biosynthesis of the sesquiterpenoid "artemisinin" from Artemisia annua,the triterepenoid "ursolic acid" from Catharanthus roseus,and the C12,8 guaianolides from Inula hupensis and Xanthium strumarium.