1O2-mediated retrograde signaling during late embryogenesis predetermines plastid differentiation in seedlings by recruiting abscisic acid.

Plastid development in seedlings of Arabidopsis thaliana is affected by the transfer of 1O2-mediated retrograde signals from the plastid to the nucleus and changes in nuclear gene expression during late embryogenesis. The potential impact of these mechanisms on plastid differentiation is maintained throughout seed dormancy and becomes effective only after seed germination. Inactivation of the 2 nuclear-encoded plastid proteins EXECUTER1 and EXECUTER2 blocks 1O2-mediated retrograde signaling before the onset of dormancy and impairs normal plastid formation in germinating seeds. This long-term effect of 1O2 retrograde signaling depends on the recruitment of abscisic acid (ABA) during seedling development. Unexpectedly ABA acts as a positive regulator of plastid formation in etiolated and light-grown seedlings. [ABSTRACT FROM AUTHOR]