Fig. 3

VIGS knock-down of NbINO activity in N. benthamiana ovules. a Ovary of control carpel shows round and symmetrical ovules packed tightly on the placenta. b In a representative knock-down carpel the ovules are variable in shape and some are incompletely formed (examples indicated with arrowheads). Ovules shown in c-e, i are from control plants and f-h, j are knock-down ovules at similar stages. In c and f the integument appears as a thickening of the chalazal area and causes bending of the ovule primordium. The integument grows asymmetrically (d) while in knock-down ovules (g) growth of the integument is reduced. At maturity (e) the nucellus is no longer visible and ovules appear isodiametric. Knock-down ovules (h) are variable in shape and some are aberrant, with the nucellus protruding from a variable integument. The large cells of the outer cell layer of the integument (arrowhead) visible in i are only covering the basal part of the integument in j. Smaller dense cells form the outermost layer of the distal part of the integument (arrow). k Arabidopsis ats ino double mutant ovule resembles the VIGS knock-down tobacco ovules. i: integument; f: funiculus; n: nucellus; mp: micropyle. Scale bar in a represents 250 μm in a, b; 50 μm in c, f; 40 μm in d, g, k; 125 μm in e; 100 μm in h; 80 μm in i, j