(A) Branches of Col-0 WT, rec8 -/-, REC8:GFP in rec8-/- background, KINGBIRD in Col-0 WT background. While rec8 -/- shows short, thin and sterile siliques (magenta arrow head), REC8:GFP and KINGBIRD present WT-like, elongated and thick siliques (white arrow heads). (B) Open siliques of Col-0 WT, rec8 -/-, REC8:GFP in rec8-/- background, KINGBIRD in Col-0 WT background. Col-0 WT, REC8:GFP and KINGBIRD form round, turgid and fully developed seeds (white arrow heads), whereas rec8 -/- presents dry and aborted seeds (magenta arrow head). (C) Anthers stained with Peterson staining (Peterson et al., 2010). Col-0 WT, REC8:GFP and KINGBIRD only produce viable pollen, while high rates of aborted pollen (blue) produced by rec8 -/- are visible inside the pollen sacs. (D) Rate of seed abortion (%). (E) Rate of aborted pollen in (%). (F) Cell spreads of Col-0 WT, rec8 -/-, REC8:GFP in rec8-/- background, TagRFP-TUB4 in Col-0 WT background and TagRFP:TUA5 in Col-0 WT background. The figure shows a selection of the main meiotic phases. rec8-/- starts to show defects from diplotene onwards, with the presence of univalent at metaphase I, and the consequent miss-segregation of chromosomes, which leads to the formation of micronuclei and unbalanced tetrads. The meiotic progression is restored in rec8-/- expressing REC8:GFP and it is not disrupted in TagRFP:TUB4 and TagRFP:TUA5 in Col-WT background. Both of the constructs generated balanced and viable gametes.