Maternal epigenetic regulation of embryonic patterning in plants.

Embryogenesis occurs within a specialized microenvironment established by maternal tissues that has long been thought to be crucial for supporting embryonic development. However, the maternal epigenetic mechanisms that regulate offspring development remain unclear. Here we profiled the H3K27me3 landscape in maternal integuments and demonstrated that epigenetic changes in maternal tissues shape embryonic patterning. Dynamic changes in H3K27me3 in the integuments are crucial for the activation of the auxin-transport genes AUX1 and LAX1, which allow auxin to accumulate in the micropylar integuments to which the embryo attaches. Deficiencies in H3K27me3 demethylase activity or AUX1/LAX1 expression reduce auxin levels in the micropylar integuments. This disrupts maternal-to-embryo auxin transport, leading to reduced auxin levels in the embryo and thus perturbing embryonic patterning. Our findings reveal a previously unrecognized mechanism of maternal epigenetic regulation that governs embryonic patterning.