White Panicle2 encoding thioredoxin z, regulates plastid RNA editing by interacting with Multiple Organellar RNA Editing Factors in rice.

• Thioredoxins (TRXs) occur in plant chloroplasts as complex disulphide oxidoreductases. Although many biological processes are regulated by thioredoxins, the regulatory mechanism of chloroplast TRXs are largely unknown. • Here we report a rice white panicle2 mutant caused by a mutation in thioredoxin z gene, an ortholog of AtTRX z in Arabidopsis. white panicle2 (wp2) seedlings exhibited a high temperature sensitive albinic phenotype. • We found that plastid multiple organellar RNA editing factors (MORFs) were the regulatory targets of thioredoxin z. We showed that OsTRX z protein physically interacts with OsMORFs in a redox-dependent manner and that the redox state of a conserved cysteine in the MORF box is essential for MORF-MORF interactions. wp2 and Ostrx z knockout lines show reduced editing efficiencies in many plastidial-encoded genes especially under high temperature conditions. An Arabidopsis trx z mutant also exhibited significantly reduced chloroplast RNA editing. • Our combined results suggest that thioredoxin z regulate chloroplast RNA editing in plants by controlling the redox state of MORFs.