(A) Leaves of wild-type, nga1,2,3,4, 35S:miR319a and nga1,2,3,4 35S:miR319a and 35S:miR319a/35S:amiR-NGA leaves illustrating the synergistic effect on leaf marginal growth when both the CIN-TCP and NGATHA gene activities are reduced (for data on the effect of miR319a and amiR-NGA on the expression of targets and related gene family members see Figure 1—source data 4). (B) Representative wild-type, 35S:amiR-NGA, 35S:miR319a, and 35S:miR319a/35S:amiR-NGA plants grown for 25 days under short-day (SD) conditions. Leaf expansion is delayed, and the leaf initiation rate is decreased in 35S:miR319a/35S:amiR-NGA lines. (C) From left to right shown are the first leaves of wild-type, 35S:amiR-NGA, 35S:miR319a, and 35S:miR319a/35S:amiR-NGA plants grown for 25 days, and the rightmost is the first leaf of 35S:miR319a/35S:amiR-NGA plant grown for 43 days. The first leaves of wild-type, 35S:amiR-NGA and 35S:miR319a plants have reached their maximum sizes after 25 days of growth while the first leaf of 35S:miR319a/35S:amiR-NGA plant continues to grow from the margins reaching a large and complex shape with continued marginal growth, photographed here after 43 days. (D1–D2) Third leaf of a long-day (LD) grown 35S:miR319a/35S:amiR-NGA plant marked with nail polish (arrows; light blue and dark blue), demonstrating the growth from the margins in 21 days. (E1–H3) Floral organs from wild-type (E1, F1, G1, H1) and 35S:miR319a/35S:amiR-NGA (E2, F2, G2, H2, H3) plants, illustrating the continued growth from organ tips when CIN-TCP and NGA gene activities are compromised. Sepals (E1, E2), petals (F1, F2), stamens (G1, G2), and gynoecia (H1, H2, H3) are shown. Scale bars: A-B, D2, 5 mm; C, 2 mm; D1, E1-H3. 1 mm.