Mutation in Rice Results in Cell Death, Enhanced Disease-Resistance, Altered Seed Dormancy and Development.

Lesion mimic mutants display spontaneous cell death, and thus are valuable for understanding the molecular mechanism of cell death and disease resistance. Although a lot of such mutants have been characterized in rice, the relationship between lesion formation and abscisic acid (ABA) synthesis pathway is not reported. In the present study, we identified a rice mutant, (), exhibiting spontaneous cell death, pre-harvest sprouting, enhanced growth, and resistance to rice bacterial and blast diseases. Cell death in the mutant was accompanied with excessive accumulation of HO. Enhanced disease resistance was associated with cell death and upregulation of defense-related genes. Map-based cloning identified a G-to-A point mutation resulting in a D-to-N substitution at the amino acid position 110 of OsABA2 (LOC_Os03g59610) in . Knock-out of through CRISPR/Cas9 led to phenotypes similar to those of . Consistent with the function of in ABA biosynthesis, ABA level in the mutant was significantly reduced. Moreover, exogenous application of ABA could rescue all the mutant phenotypes of . Taken together, our data linked ABA deficiency to cell death and provided insight into the role of ABA in rice disease resistance.