Evolution and diversification of the momilactone biosynthetic gene cluster in the genusOryza

Abstract

ABSTRACTPlants are master chemists and collectively are able to produce hundreds of thousands of different organic compounds. The genes underlying the biosynthesis of many specialized metabolites are organized in biosynthetic gene clusters (BGCs), which is hypothesized to ensure their faithful co-inheritance and to facilitate their coordinated expression. In rice, momilactones are diterpenoids that act in plant defence and various organismic interactions. Many of the genes essential for momilactone biosynthesis are grouped in a biosynthetic gene cluster. Here, we apply comparative genomics of diploid and allotetraploidOryzaspecies to reconstruct the species-specific architecture, evolutionary trajectory, and sub-functionalisation of the momilactone biosynthetic gene cluster (MBGC) in theOryzagenus. Our data show that the evolution of the MBGC is marked by lineage-specific rearrangements and gene copy number variation, as well as by pseudogenization and occasional cluster loss. We identified a distinct cluster architecture inO. coarctata, which represents the first instance of an alternative architecture of the MBGC inOryzaand strengthens the idea of a common origin of the cluster inOryzaand the distantly related genusEchinochloa. Our research illustrates the evolutionary and functional dynamics of a biosynthetic gene cluster within a plant genus.