Deficiency of mitochondrial outer membrane protein 64 confers rice resistance to both piercing-sucking and chewing insects in rice.

ABSTRACT

The brown planthopper (BPH) and striped stem borer (SSB) are the most devastating insect pests in rice (Oryza sativa) producing areas. Screening for endogenous resistant genes is the most practical strategy for rice insect-resistance breeding. Forty-five mutants showing high resistance against BPH were identified in a rice T-DNA insertion population (11,000 putative homozygous lines) after 4 years of large-scale field BPH-resistance phenotype screening. Detailed analysis showed that deficiency of rice mitochondrial outer membrane protein 64 (OM64) gene resulted in increased resistance to BPH. Mitochondrial outer membrane protein 64 protein is located in the outer mitochondrial membrane by subcellular localization and its deficiency constitutively activated hydrogen peroxide (H2 O2 ) signaling, which stimulated antibiosis and tolerance to BPH. The om64 mutant also showed enhanced resistance to SSB, a chewing insect, which was due to promotion of Jasmonic acid biosynthesis and related responses. Importantly, om64 plants presented no significant changes in rice yield-related characters. This study confirmed OM64 as a negative regulator of rice herbivore resistance through regulating H2 O2 production. Mitochondrial outer membrane protein 64 is a potentially efficient candidate to improve BPH and SSB resistance through gene deletion. Why the om64 mutant was resistant to both piercing-sucking and chewing insects via a gene deficiency in mitochondria is discussed.