Abstract

Geranylgeranyl diphosphate is a precursor for both chlorophyll and diterpenoid biosynthesis in the plastid, as the substrate of geranylgeranyl reductase and copalyl diphosphate synthases (CPSs), respectively. Light-harvesting-like protein 3 (LIL3) participates in chlorophyll formation, but its role in other isoprenoid pathways remains unclear. Here, we show that loss of OsLIL3 function altered the expression of diterpenoid biosynthetic genes and reduced the accumulation of diterpenoids in rice ( Oryza sativa ). Protein–protein interaction assays demonstrated that OsLIL3 physically interacts with OsCPS2 in plastids. The Oslil3 mutant showed enhanced susceptibility to Xanthomonas oryzae pv. oryzae and brown planthoppers ( Nilaparvata lugens ), and natural variations at OsLIL3 were associated with different resistances among rice accessions. Methyl jasmonate suppressed OsLIL3 expression in shoots while inducing OsCPS2 expression. These findings suggest that OsLIL3 contributes to resistance, probably by regulating diterpenoid phytoalexin biosynthesis through interacting with OsCPS2, revealing a connection between chlorophyll and diterpenoid biosynthesis from plastidial isoprenoid metabolism.