Meiotic exit in <i>Arabidopsis</i> is driven by P-body–mediated inhibition of translation

Abstract

Meiosis, at the transition between diploid and haploid life cycle phases, is accompanied by reprograming of cell division machinery and followed by a transition back to mitosis. We show that, in <i>Arabidopsis</i>, this transition is driven by inhibition of translation, achieved by a mechanism that involves processing bodies (P-bodies). During the second meiotic division, the meiosis-specific protein THREE-DIVISION MUTANT 1 (TDM1) is incorporated into P-bodies through interaction with SUPPRESSOR WITH MORPHOGENETIC EFFECTS ON GENITALIA 7 (SMG7). TDM1 attracts eIF4F, the main translation initiation complex, temporarily sequestering it in P-bodies and inhibiting translation. The failure of <i>tdm1</i> mutants to terminate meiosis can be overcome by chemical inhibition of translation. We propose that TDM1-containing P-bodies down-regulate expression of meiotic transcripts to facilitate transition of cell fates to postmeiotic gametophyte differentiation.