Transcriptome responses to temperature, water availability and photoperiod are conserved among mature trees of two divergent Douglas-fir provenances from a coastal and an interior habitat.

Moritz Hess,Ingo Ensminger,Laura Verena Junker,Henning Wildhagen

doi:10.1186/s12864-016-3022-6

Abstract

BackgroundLocal adaptation and phenotypic plasticity are important components of plant responses to variations in environmental conditions. While local adaptation has been widely studied in trees, little is known about plasticity of gene expression in adult trees in response to ever changing environmental conditions in natural habitats. Here we investigate plasticity of gene expression in needle tissue between two Douglas-fir provenances represented by 25 adult trees using deep RNA sequencing (RNA-Seq).ResultsUsing linear mixed models we investigated the effect of temperature, soil water availability and photoperiod on the abundance of 59189 detected transcripts. Expression of more than 80 % of all identified transcripts revealed a response to variations in environmental conditions in the field. GO term overrepresentation analysis revealed gene expression responses to temperature, soil water availability and photoperiod that are highly conserved among many plant taxa. However, expression differences between the two Douglas-fir provenances were rather small compared to the expression differences observed between individual trees. Although the effect of environment on global transcript expression was high, the observed genotype by environment (GxE) interaction of gene expression was surprisingly low, since only 21 of all detected transcripts showed a GxE interaction.ConclusionsThe majority of the transcriptome responses in plant leaf tissue is driven by variations in environmental conditions. The small variation between individuals and populations suggests strong conservation of this response within Douglas-fir. Therefore we conclude that plastic transcriptome responses to variations in environmental conditions are only weakly affected by local adaptation in Douglas-fir.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3022-6) contains supplementary material, which is available to authorized users.

Highlights

Local adaptation and phenotypic plasticity are important components of plant responses to variations in environmental conditions
Potential genomic targets of adaptation to climate have been identified by linking single nucleotide polymorphisms (SNP) to local climate or by identification of associations among SNPs and traits that are known to co-vary with climatic clines, e.g. bud set and cold resistance (Picea sitchensis [8]), carbon isotope discrimination (Pinus taeda [9]) or cold hardiness (Pseudotsuga menziesii [10])
Gene Ontology (GO) annotations were identified for 34 k putative unique transcripts (PUT) using BLAST2GO. 6330 PLAZA gene families were identified in the set of all detected PUTs

Summary

Introduction

Local adaptation and phenotypic plasticity are important components of plant responses to variations in environmental conditions. While local adaptation has been widely studied in trees, little is known about plasticity of gene expression in adult trees in response to ever changing environmental conditions in natural habitats. Global transcriptome analysis has been extensively used in studies with highly controlled conditions to characterize plasticity and diversity of gene expression metabolism in response to abiotic factors among different populations Few studies investigated genome-wide gene expression responses to abiotic stimuli in natural environments [21, 19, 22,23,24,25] and studies in perennial, woody plants are exceptionally rare but see e.g. Few studies investigated genome-wide gene expression responses to abiotic stimuli in natural environments [21, 19, 22,23,24,25] and studies in perennial, woody plants are exceptionally rare but see e.g. [19] on Picea sitchensis, [22] on Vitis vinifera and [25] on Populus euphratica

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