Characterization Of A Spotted-leaf Mutant Spl6 In Rice

Plant spotted-leaf mutants spontaneously exhibit hypersensitive response-like cell death in absence of pathogens,and are of great significance in dissecting the molecular mechanisms of disease resistance in plants.In this study,reactive oxygen species(ROS)were accumulated in spl6 leaves,meanwhile,activities of ROS scavenging enzymes such as CAT and POD significantly changed in spl6,indicating that the imbalance of ROS metabolism might trigger hypersensitive response in spl6.The resistance against 6 races was significantly enhanced in the spl6 mutant,indicating that the mutant displays a broad-spectrum resistance to rice bacterial blight.Additionally,real-time PCR-based assay showed that the transcriptional levels of 6 key regulators in salicylic acid(SA)and 2 key regulators in jasmonic acid(JA)signaling pathways were up-regulated in spl6.These results indicated that spl6 mutation might activate both SA and JA pathways and consequently trigger systematic defense response in plants.Genomic sequence analysis revealed that only the 7th exon of LOC_Os06g03940 carries a single-nucleotide transition(A to G).LOC_Os06g03940 encodes an ATPase associated with various cellular activities type(AAA)protein.The A-G base substitution was identified in AAA domain,causing activities of total ATPase degradation.SPL6 expression is constitutive in most tissues.In addition,the protein located in chloroplast of rice protoplasts.