Location: Grape Genetics ResearchTitle: Leaves as composites of latent developmental and evolutionary shapes Author
|Chitwood, Daniel - Danforth Plant Science Center|
|Klein, Laura - St Louis University|
|Miller, Allison - St Louis University|
Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/31/2015
Publication Date: 4/1/2016
Citation: Chitwood, D., Klein, L., Miller, A., Londo, J.P. 2016. Leaves as composites of latent developmental and evolutionary shapes. New Phytologist. 210(1):343-355.
Interpretive Summary: In the plant kingdom, leaf shapes can vary in an almost unlimited way. Differences in leaf shape help plant systematics identify specific species and the use of leaf shape in grapevine is its own discipline, ampelography. Leaf shape impacts many different growth and developmental processes such as photosynthetic efficiency, canopy density, and whole plant productivity. In this study, researchers examined leaf shape in wild and cultivated grapevine using a set of 17 different leaf landmarks. A single representative cane was found on every wild grapevine in the USDA-ARS cold hardy grapevine germplasm. Additionally, scans of the entire collection of the USDA-ARS Vitis vinifera grapevine germplasm were used. The results demonstrate there are distinct patterns in the location of the landmarks in the wild. Cultivated grapevine leaves create shapes that are difficult to interpret with the naked eye. When you combine these latent, or hidden shapes, they produce the overall combined shape we can see. Examining the overall patterns of these latent shapes demonstrates the key differences between grapevine species. Understanding these shape differences give us new information about patterns of leaf development and evolutionary trends in grapevine. These results also provide the foundation of leaf pattern differences that can be examined with regard to species specific differences in foliar abiotic and biotic stress resistance.
Technical Abstract: Across plants, leaves exhibit profound diversity in shape. As a single leaf expands, its shape is in constant flux. Additionally, plants may also produce leaves with different shapes at successive nodes. Because leaf shape can vary in many different ways, theoretically the effects of distinct processes are separable, even within the shape of a single leaf. Here, we measure the shapes of >3,200 leaves representing >270 vines from wild relatives of domesticated grape. We isolate latent shapes embedded within the overall shape of leaves that can predict developmental stages independent from species identity and vice versa. Shapes predictive of development are then used to stage leaves from 1,200 varieties of domesticated grape, revealing that changes in timing underlie leaf shape diversity. Our results indicate distinct latent shapes combine to produce a composite morphology in leaves, and that developmental and evolutionary contributions to shape vary independently from each other. Our results have implications for taxonomy and assessments of biodiversity, isolating specifically those features most defining species from conserved, developmental shapes that evolve more slowly. Specific shape features can define outputs from distinct molecular pathways that change leaf morphology over evolutionary versus developmental timescales. Within a single leaf are distinct components of shape that are affected by distinct processes.