Figure 4

Trichome patterning in A. alpina . A-C) Three developmental stages of an A. alpina leaf. D) Aattg1-1 leaves. E) Meta leaf generated using TrichEratops integrating the relative position of trichomes from 22 young leaves [66]. Red dots are incipient trichomes, blue dots intermediate developmental stages and black dots represent mature trichomes. Note that incipient trichomes are found in a region in which already mature trichomes have developed. F) Boxplot depicting the relative position (0 is the base of the leaf and 100 the tip of the leaf) of three developmental classes of trichome development. Note that the average position of the three developmental classes is clearly distinct. “*” indicate that all three classes are significantly different from each other according to Student’s t-test (P < 0.001). G) SEM picture of a leaf 3 from the side showing that trichomes are found on the abaxial and adaxial side. H) Average minimum distance to the nearest neighboring trichome on different regions of leaf 2. Distances between smaller trichomes (class 1) are shown in orange, distances between larger trichomes (class 2) in pink and distances between the two classes in grey. I) Average minimum distance to the nearest neighboring trichome on leaves 1 to 6. J) SEM of an adult A. alpina leaf showing the large (pink arrow) and the small classes of trichomes (orange arrow). Scale bar = 100 μm in A,B. Scale bar = 500 μm in C. Scale bar = 1 mm in D,E.