Latent developmental and evolutionary shapes embedded within the grapevine leaf

Abstract

Summary Across plants, leaves exhibit profound diversity in shape. As a single leaf expands, its shape is in constant flux. Plants may also produce leaves with different shapes at successive nodes. In addition, leaf shape varies among individuals, populations and species as a result of evolutionary processes and environmental influences.Because leaf shape can vary in many different ways, theoretically, the effects of distinct developmental and evolutionary processes are separable, even within the shape of a single leaf. Here, we measured the shapes of > 3200 leaves representing > 270 vines from wild relatives of domesticated grape (Vitis spp.) to determine whether leaf shapes attributable to genetics and development are separable from each other.We isolated latent shapes (multivariate signatures that vary independently from each other) embedded within the overall shape of leaves. These latent shapes can predict developmental stages independent from species identity and vice versa. Shapes predictive of development were then used to stage leaves from 1200 varieties of domesticated grape (Vitis vinifera), revealing that changes in timing underlie leaf shape diversity.Our results indicate that distinct latent shapes combine to produce a composite morphology in leaves, and that developmental and evolutionary contributions to shape vary independently from each other.

Climate and Developmental Plasticity: Interannual Variability in Grapevine Leaf Morphology

“…In a previous study, we measured leaves from the 2012-2013 growing season with 17 landmarks describing the lobes, sinuses, and major vein branching points on both sides of the leaf (Chitwood et al, 2015b). Unlike in animal studies, allometry (changes in shape that vary by organ size, or the growth of body parts at different rates) is not a straightforward concept when applied to plants because of their iterative growth.…”

“…leaves and match leaves, from the same vines and same developmental stages, between the 2012-2013 (Chitwood et al, 2015b) and 2014-2015 growing seasons. The depth of the distal sinus, specifically, is a shape feature that has been altered in all Vitis species analyzed across different developmental contexts.…”

Left–right leaf asymmetry in decussate and distichous phyllotactic systems

“…Next, we analysed more than 3000 leaf pairs from 20 different Vitis and Ampelopsis species and hybrids from a germplasm collection maintained by the USDA in Geneva, NY, USA. This previously published dataset [20] analysed leaf shape in more than 270 vines by collecting all the leaves from a single shoot and recording their order (figure 5c). Using 17 homologous landmarks superimposed using a Procrustes analysis, both symmetric and asymmetric sources of shape variance are analysed, but asymmetry is almost exclusively restricted to a specific PC, in this case PC4 which explains 10.5% of the total shape variance (figure 5d).…”

“…Leaves from 20 different grapevine species and hybrids (Vitis and Ampelopsis spp.) were collected from more than 270 vines in the USDA Vitis germplasm collection in Geneva, NY, USA, in June 2013 [20]. A single shoot was sampled from each vine, the leaves dissected, scanned and their position in the shoot noted.…”

“…Landmarks and their order were as follows: (i) petiolar junction, (ii) midvein tip, (iii) left distal sinus, (iv) right distal sinus, (v) left distal lobe tip, (vi) right distal lobe tip, (vii) left proximal sinus, (viii) right proximal sinus, (ix) left proximal lobe tip, (x) right proximal lobe tip, (xi) left terminus petiolar vein, (xii) right terminus petiolar vein, (xiii) branch point midvein, (xiv) branch point left distal vein, (xv) branch point right distal vein, (xvi) branch point left proximal vein, (xvii) branch point right proximal vein (see [20] for a visualization of landmark position). Using ggplot2 [30] in R [31], graphs for landmarks from each image were visually checked for errors.…”