Figure 2.

P. tremula × P. alba Plants during Short Day–Induced Bud Set (8 h/Day Photoperiod).

(A) Close-up of the apex of an actively growing wild-type plant under long-day conditions. Two stipules are formed together with each leaf but are too small to be seen at this stage.

(B) Close-up of the apex of a bud-setting wild-type plant with formation of the first bud scales after 4 weeks under short-day conditions. Arrows point to the initiated bud scales.

(C) Close-up of the apical bud of a wild-type plant grown for 6 weeks under short-day conditions. Arrows point to the bud scales that have enlarged and started to encase the embryonic leaves.

(D) Apical part of a wild-type plant grown under long-day conditions.

(E) Apical part of a wild-type plant grown for 6 weeks under short-day conditions. The arrow marks the last mature leaf below the bud. The inset shows an enlargement of the apex.

(F) Apical part of a PtABI3-overexpressing plant grown for 6 weeks under short-day conditions. The arrow marks the last mature leaf below the bud. The inset shows an enlargement of the apex.

Bars in (A) to (C) = 1 mm.