Summary: ATP‐citrate lyases (ACL) play critical roles in tumour cell propagation, foetal development and growth, and histone acetylation in human and animals. Here, we report a novel function of ACL in cell death‐mediated pathogen defence responses in rice. Using ethyl methanesulphonate (EMS) mutagenesis and map‐based cloning, we identified an Oryza sativa ACL‐A2 mutant allele, termed spotted leaf 30‐1 (spl30‐1), in which an A‐to‐T transversion converts an Asn at position 343 to a Tyr (N343Y), causing a recessive mutation that led to a lesion mimic phenotype. Compared to wild‐type plants, spl30‐1 significantly reduces ACL enzymatic activity, accumulates high reactive oxygen species and increases degradation rate of nuclear deoxyribonucleic acids. CRISPR/Cas9‐mediated insertion/deletion mutation analysis and complementation assay confirmed that the phenotype of spl30‐1 resulted from the defective function of OsACL‐A2 protein. We further biochemically identified that the N343Y mutation caused a significant degradation of SPL30^N343Y in a ubiquitin‐26S proteasome system (UPS)‐dependent manner without alteration in transcripts of OsACL‐A2 in spl30‐1. Transcriptome analysis identified a number of up‐regulated genes associated with pathogen defence responses in recessive mutants of OsACL‐A2, implying its role in innate immunity. Suppressor mutant screen suggested that OsSL, which encodes a P450 monooxygenase protein, acted as a downstream key regulator in spl30‐1‐mediated pathogen defence responses. Taken together, our study discovered a novel role of OsACL‐A2 in negatively regulating innate immune responses in rice.

Background: Flag leaf is the most essential organ for photosynthesis in rice and its size plays an important role in rice breeding for ideal plant-type. Flag leaf size affect photosynthesis to a certain extent, thereby influencing rice production. Several genes controlling leaf size and shape have been identified with mutants. Although a number of quantitative trait loci (QTLs) for leaf size and shape have been detected on 12 chromosomes with different populations of rice, few of them were cloned. Results: The pair-wise correlation analysis was conducted on length, width and length-width ratio of the flag leaf, and yield per plant in the core recombinant inbred lines of Liang-You-Pei-Jiu (LYP9) developed in Hainan and Hangzhou. There were significant correlations among the three flag leaf size and shape traits. Interestingly, a positive correlation was found between flag leaf width and yield per plant. Based on the high-resolution linkage map we constructed before, 43 QTLs were detected for three flag leaf size and shape traits and yield per plant, among which 31 QTLs were unreported so far. Seven QTLs were identified common in two environments. And qFLW7.2, a new major QTL for flag leaf width, was fine mapped within 27.1 kb region on chromosome 7. Both qFLW7.2 and qPY7 were located in the interval of 45.30 ~ 53.34 cM on chromosome 7, which coincided with the relationship between yield per plant (PY) and flag leaf width (FLW). Conclusion: qFLW7.2, which explained 14% of the phenotypic variation, increased flag leaf width with 93–11 allele. Two candidate genes were selected based on sequence variation and expression difference between two parents, which facilitated further QTL cloning and molecular breeding in super rice.