Leaf shape in Populus tremula is a complex, omnigenic trait

Mähler, N., Schiffthaler, B., Robinson, K. M., Terebieniec, B. K., Vučak, M., Mannapperuma, C., Bailey, M. E.S. , Jansson, S., Hvidsten, T. R. and Street, N. R. (2020) Leaf shape in Populus tremula is a complex, omnigenic trait. Ecology and Evolution, 10(21), pp. 11922-11940. (doi: 10.1002/ece3.6691)

Abstract

Leaf shape is a defining feature of how we recognize and classify plant species. Although there is extensive variation in leaf shape within many species, few studies have disentangled the underlying genetic architecture. We characterized the genetic architecture of leaf shape variation in Eurasian aspen (Populus tremula L.) by performing genome‐wide association study (GWAS) for physiognomy traits. To ascertain the roles of identified GWAS candidate genes within the leaf development transcriptional program, we generated RNA‐Seq data that we used to perform gene co‐expression network analyses from a developmental series, which is publicly available within the PlantGenIE resource. We additionally used existing gene expression measurements across the population to analyze GWAS candidate genes in the context of a population‐wide co‐expression network and to identify genes that were differentially expressed between groups of individuals with contrasting leaf shapes. These data were integrated with expression GWAS (eQTL) results to define a set of candidate genes associated with leaf shape variation. Our results identified no clear adaptive link to leaf shape variation and indicate that leaf shape traits are genetically complex, likely determined by numerous small‐effect variations in gene expression. Genes associated with shape variation were peripheral within the population‐wide co‐expression network, were not highly connected within the leaf development co‐expression network, and exhibited signatures of relaxed selection. As such, our results are consistent with the omnigenic model.

• Item Type: Articles
• Additional Information: NRS, BT, and KMR were supported by the Trees and Crops for the Future (TC4F) project. NM, BS, and CM were supported by the Knut and Alice Wallenberg Foundation and the Vinnova UPSC Centre for Forest Biotechnology. This work was supported by the Trygger Foundation (#CTS 12:471) and Gunnar och Ruth Björkmans fond för Norrländsk Botanisk Forskning. The authors acknowledge support from the Umeå Plant Science Centre Bioinformatics Platform (UPSCb), the Science for Life Laboratory (SciLifeLab), and the National Genomics Infrastructure (NGI).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Vucak, Mr Matej and Bailey, Dr Mark
• Authors: Mähler, N., Schiffthaler, B., Robinson, K. M., Terebieniec, B. K., Vučak, M., Mannapperuma, C., Bailey, M. E.S., Jansson, S., Hvidsten, T. R., and Street, N. R.
• College/School: College of Medical Veterinary and Life Sciences > School of Molecular Biosciences; College of Medical Veterinary and Life Sciences > School of Infection & Immunity > Centre for Virus Research
• Journal Name: Ecology and Evolution
• Publisher: Wiley
• ISSN: 2045-7758
• ISSN (Online): 2045-7758
• Published Online: 13 October 2020
• Copyright Holders: Copyright © 2020 The Authors
• First Published: First published in Ecology and Evolution 10(21): 11922-11940
• Publisher Policy: Reproduced under a Creative Commons License