Resolving Distinct Genetic Regulators of Tomato Leaf Shape within a Heteroblastic and Ontogenetic Context

Abstract

Leaf shape is mutable, changing in ways modulated by both development and environment within genotypes. A complete model of leaf phenotype would incorporate the changes in leaf shape during juvenile-to-adult phase transitions and the ontogeny of each leaf. Here, we provide a morphometric description of >33,000 leaflets from a set of tomato (Solanum spp) introgression lines grown under controlled environment conditions. We first compare the shape of these leaves, arising during vegetative development, with >11,000 previously published leaflets from a field setting and >11,000 leaflets from wild tomato relatives. We then quantify the changes in shape, across ontogeny, for successive leaves in the heteroblastic series. Using principal component analysis, we then separate genetic effects modulating (1) the overall shape of all leaves versus (2) the shape of specific leaves in the series, finding the former more heritable than the latter and comparing quantitative trait loci regulating each. Our results demonstrate that phenotype is highly contextual and that unbiased assessments of phenotype, for quantitative genetic or other purposes, would ideally sample the many developmental and environmental factors that modulate it.

Analyzing Fluctuating Asymmetry with Geometric Morphometrics: Concepts, Methods, and Applications

“…This method for separating symmetric and asymmetric components of variation has been used in studies to characterize asymmetry and shape variation in plant leaves and other structures [191,260,[299][300][301][302][303][304].…”

eQTL Regulating Transcript Levels Associated with Diverse Biological Processes in Tomato

“…To connect detected eQTL with leaf and hypocotyl phenotypes under two different environmental conditions, we correlated transcript abundance with leaf number, leaf complexity (as measured in Chitwood et al, 2014), and hypocotyl length phenotypes of the ILs grown under simulated sun and shade conditions. Significant correlations with transcript abundance patterns were identified for all three phenotypes analyzed under both treatments (Supplemental Table S5).…”

“…S8, A and B; Supplemental Data Set 2 in Chitwood et al, 2014). For the leaf complexity trait, correlations were reversed compared to leaf number (Supplemental Fig.…”

“…Normalized estimated read counts with 3 to 4 independent replicates per IL were log2 transformed prior to the analyses. Leaf number and complexity were collected from the ILs as outlined in Chitwood et al (2014) under both sun and shade treatments. Hypocotyl lengths were measured as detailed above.…”

Climate and Developmental Plasticity: Interannual Variability in Grapevine Leaf Morphology

“…Beyond the dynamic shape changes in a single leaf, plants produce different types of leaves at different nodes, reflecting the temporal development of the meristem from which they arise, a process known as heteroblasty (Goebel, 1900;Ashby, 1948;Poethig, 1990Poethig, , 2010Jones, 1993;Kerstetter and Poethig, 1998;Diggle, 2002). Changes in the timing of the heteroblastic progression of leaf shape can create evolutionary differences between species, a process known as heterochrony (Chitwood et al, 2012(Chitwood et al, , 2014bCartolano et al, 2015).…”