DCFH-DA and Mito-Tracker Red double-staining showing mitochondria constitutively accumulating alongside the filiform apparatus (FA) adjacent region (FAAR) in synergid cells (black arrowheads). ROS are undetectable in synergid cells before pollination ( e ) and accumulate at the mitochondria-enriched FAAR in the persistent synergid cell at 20 HAP.
