Genetical genomics of Populus leaf shape variation
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Data
2015
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Background: Leaf morphology varies extensively among plant species and is under strong genetic control.
Mutagenic screens in model systems have identified genes and established molecular mechanisms regulating leaf
initiation, development, and shape. However, it is not known whether this diversity across plant species is related to
naturally occurring variation at these genes. Quantitative trait locus (QTL) analysis has revealed a polygenic control
for leaf shape variation in different species suggesting that loci discovered by mutagenesis may only explain part of
the naturally occurring variation in leaf shape. Here we undertook a genetical genomics study in a poplar intersectional
pseudo-backcross pedigree to identify genetic factors controlling leaf shape. The approach combined QTL discovery in a
genetic linkage map anchored to the Populus trichocarpa reference genome sequence and transcriptome analysis.
Results: A major QTL for leaf lamina width and length:width ratio was identified in multiple experiments that confirmed
its stability. A transcriptome analysis of expanding leaf tissue contrasted gene expression between individuals with
alternative QTL alleles, and identified an ADP-ribosylation factor (ARF) GTPase (PtARF1) as a candidate gene for regulating
leaf morphology in this pedigree. ARF GTPases are critical elements in the vesicular trafficking machinery. Disruption of
the vesicular trafficking function of ARF by the pharmacological agent Brefeldin A (BFA) altered leaf lateral growth in the
narrow-leaf P. trichocarpa suggesting a molecular mechanism of leaf shape determination. Inhibition of the vesicular
trafficking processes by BFA interferes with cycling of PIN proteins and causes their accumulation in intercellular
compartments abolishing polar localization and disrupting normal auxin flux with potential effects on leaf expansion.
Conclusions: In other model systems, ARF proteins have been shown to control the localization of auxin efflux carriers,
which function to establish auxin gradients and apical-basal cell polarity in developing plant organs. Our results support
a model where PtARF1 transcript abundance changes the dynamics of endocytosis-mediated PIN localization in leaf cells,
thus affecting lateral auxin flux and subsequently lamina leaf expansion. This suggests that evolution of differential
cellular polarity plays a significant role in leaf morphological variation observed in subgenera of genus Populus.
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Leaf morphology, ADP-ribosylation factor, QTL analysis, Populus trichocarpa, Expression QTL, Genomics
Citação
DROST, Derek R.; PURANIK, Swati; NOVAES, Evandro; NOVAES, Carolina R. D. B.; Dervinis, Christopher; GAILING, Oliver; KIRST, Matias. Genetical genomics of Populus leaf shape variation. BMC Plant Biology, New York, v. 15, p. 166, 2015.