title: The developmental trajectory of leaflet morphology in wild tomato species.
abstract: Leaves between species vary in their size, serration, complexity, and shape. However, phylogeny is not the only predictor of leaf morphology. The shape of a leaf is the result of intricate developmental processes, including heteroblastic progression (changes in leaf size and shape at different nodes) and the developmental stage of an organ. The leaflets that arise from complex leaves are additionally modified by their positioning along the proximal-distal axis of a leaf and whether they fall on the left or right side of leaves. Even further, leaves are environmentally responsive, and their final shape is influenced by environmental inputs. Here, we comprehensively describe differences in leaflet shape between wild tomato (Solanum section Lycopersicon) species using a principal component analysis on elliptical Fourier descriptors arising from >11,000 sampled leaflets. We leverage differences in developmental rate to approximate a developmental series, which allows us to resolve the confounding differences in intrinsic leaflet form and developmental stage along positions of the heteroblastic leaf series and proximal-distal axis of leaves. We find that the resulting developmental trajectory of organs at different positions along these axes are useful for describing the changes in leaflet shape that occur during the shade avoidance response in tomato. We argue that it is the developmental trajectory, the changes in shape that occur over developmental time in organs reiterated at multiple positions, that is the relevant phenotype for discerning differences between populations and species, and to understand the underlying developmental processes that change during evolution.
authors.affiliation: Department of Plant Biology, University of California, Davis, California 95616, USA.
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Chitwood
authors.forename: Lauren R
authors.initials: LR
authors.lastname: Headland
authors.forename: Ravi
authors.initials: R
authors.lastname: Kumar
authors.forename: Jie
authors.initials: J
authors.lastname: Peng
authors.forename: Julin N
authors.initials: JN
authors.lastname: Maloof
authors.forename: Neelima R
authors.initials: NR
authors.lastname: Sinha
mesh_terms: D005075:Biological Evolution; D004777:Environment; D035264:Flowers / Q000254:growth & development / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D018551:Solanum lycopersicum / Q000235:genetics / Q000254:growth & development* / Q000502:physiology; D010641:Phenotype; D018515:Plant Leaves / Q000254:growth & development / Q000502:physiology*; D025341:Principal Component Analysis; D013045:Species Specificity; D013997:Time Factors