Evolutionary conserved cis-trans regulation machinery for diterpenoid phytoalexin production in Poaceae
Momilactones and phytocassanes, vital diterpenoid compounds in rice defense system, are maintained alongside biosynthetic gene cluster in some wild rice. However, it was not clear whether the regulatory mechanism of inducible phytoalexins exists in wild rice. This study reveals that after CuCl2 treatment, these genes are induced over time, leading to momilactone and phytocassane accumulation in various wild rice species. Transcriptome analysis identified conserved transcription factors highly associated with the expression of these genes in the clusters. Among those selected CuCl2-responsive transcription factors, Diterpenoid Phytoalexin Factor (DPF), a key regulator in cultivated rice, was found broadly conserved in wild rice, inducing phytoalexin production when introduced into cultivated rice cells. By comparing the upstream region of the phytoalexin biosynthesis gene between wild rice and cultivated rice, we found highly conserved genomic regions that retains N-box (5′-CACGAG-3′),