Deletion of Diterpenoid Biosynthetic Genes and Induces Cell Death and Enhances Bacterial Blight Resistance in Rice .

Lesion mimic mutants (LMMs) are ideal materials for studying cell death and resistance mechanisms. Here, we identified and mapped a novel rice LMM, . The exhibits a spontaneous hypersensitive response-like cell death phenotype accompanied by excessive accumulation of reactive oxygen species (ROS) and upregulated expression of pathogenesis-related genes, as well as enhanced resistance to pv. (). Using a map-based cloning strategy, a 184,916 bp deletion on chromosome 2 that overlaps with the diterpenoid biosynthetic gene cluster was identified in . Accordingly, the content of diterpenoids decreased in . In addition, lignin, one of the physical lines of plant defense, was increased in . RNA-seq analysis showed 590 significantly differentially expressed genes (DEG) between the wild-type and , 585 of which were upregulated in . Upregulated genes in were mainly enriched in the monolignol biosynthesis branches of the phenylpropanoid biosynthesis pathway, the plant-pathogen interaction pathway and the phytoalexin-specialized diterpenoid biosynthesis pathway. Taken together, our results indicate that the diterpenoid biosynthetic gene cluster on chromosome 2 is involved in immune reprogramming, which in turn regulates cell death in rice.