Abstract
Retrograde signaling from the plastid to the nucleus plays a key role in coordinating nuclear gene expression and in maintaining the correct functioning of plastids. It has been suggested that inhibitors causing plastid dysfunction generate specific plastid signals related to the inhibitors' modes of action. However, signaling molecules involved in plastid signals remain to be identified. To investigate the nature of the plastid signals generated by different treatments, we investigated whether these treatments had similar effects on plastids and on nuclear gene expression. We demonstrate that norflurazon and lincomycin treatments and the ppi2-2 mutation, which causes a defect in plastid protein import, all resulted in similar changes at the gene expression level. Furthermore, we observed that plastid RNA editing was impaired in the ppi2-2 mutant. Wild-type plants treated with norflurazon or lincomycin also exhibited defects in RNA editing in plastids. Our results indicate that these 3 treatments, which are known to induce plastid signals, affect RNA editing in plastids, suggesting an unprecedented link between plastid signaling and RNA editing.
