<i>KLU</i> suppresses megasporocyte cell fate through SWR1-mediated activation of <i>WRKY28</i> expression in <i>Arabidopsis</i>

Abstract

Significance In flowering plants, the female germ line begins as a single cell known as the megaspore mother cell (MMC) in each ovule. The mechanisms that restrict MMC fate to a single cell remain largely unknown. We show that the Arabidopsis cytochrome P450 gene KLU acts through the chromatin remodeling complex SWR1 to promote WRKY28 expression in ovule primordia. We show that WRKY28 is expressed in a few somatic cells surrounding the MMC and is required to inhibit these cells from acquiring the MMC-like cell fate. Consistent with non–cell-autonomous KLU activity, KLU -expressing cells and WRKY28 -expressing cells are neither identical nor adjacently positioned. Our study demonstrates that cell–cell interactions involving only somatic cells in ovule primordia ensure the specification of a single MMC.