Fig. 3

Comparing leaf area and the natural log of the ratio of vein-to-blade area between wild type and Witch’s Broom samples in Dakapo and Merlot varieties of grapevine. (A) Dakapo WT, (B) Dakapo WB, (C) Merlot WT, and (D) Merlot WB composite leaves generated using leaf landmarks to model leaf shapes for leaves collected across 13 nodes. Composite leaves are colored based on node, from gray (node 1 from the shoot tip) to dark blue (node 13). All samples are to the same scale, and a 1 cm scale bar is provided in the bottom left corner of (A). (E) A comparison of leaf area (cm²), as calculated using the shoelace algorithm originally described by Meister (1769) and used in Chitwood et al. (2020) to calculate leaf area in grapevine, with leaf landmark data. Mean leaf area (cm²) is represented by a black line for each sample. Dakapo WB and Merlot WB both have significantly smaller leaves (P < 0.001*** for both cases) in comparison to WT plants of the same variety. Merlot WT leaves were larger than Dakapo WT leaves (P < 0.001***), however leaf area did not differ between the two WB cases (P = 0.16). (F) A comparison of the natural log of the ratio of vein-to-blade area, an allometric indicator of leaf size that is typically more sensitive to leaf size changes than leaf area alone. Mean ln (vein-to-blade ratio) is represented by a black line for each sample. Dakapo WB and Merlot WB both have significantly higher vein-to-blade ratios (P < 0.001*** for both cases) in comparison to WT plants of the same variety. Dakapo WT leaves have a higher vein-to-blade ratio than Merlot WT leaves (P < 0.001***). Dakapo WB leaves have a higher vein-to-blade ratio than Merlot WB leaves (P < 0.001***) as well