Advances on the study of gene clusters involved in plant secondary metabolism

Genes encoding enzymes involved in the sequential biosynthesis steps of secondary metabolites are clustered together in the prokaryotic genome,also known as ‘operons’.In the genome of eukaryotes (e.g.yeasts,fungi,and insects),a set of functional genes responsible for special metabolite biosynthesis has also been discovered clustered in the chromosome.Recently,several secondary metabolic gene clusters have been identified in plants,such as Zea mays L.,Oryza sativa L.Arabidopsis thaliana(L.) Heynh.,and Solanum lycopersicum L..In this review,we summarize the identified gene clusters involved in the biosynthesis of benzoxazinoids,terpenoids,and alkaloids in plants,as well as analyze the mechanisms of gene cluster formation and regulation.In addition,the application prospects of these gene clusters are discussed.Increasing knowledge of plant metabolic gene clusters will facilitate the development of synthetic biology and metabolic engineering.