The responses of Arabidopsis lyrata ssp. petraea to environmental stimuli

Arabidopsis lyrata ssp. petraea has a fragmented distribution across Northern Eurasia, and its geographically isolated populations experience varying environmental conditions throughout the species’ range. A. l. petraea is consequently an appropriate test system to study the effects of abiotic stress on species’ distributions and for investigation of local adaptation.

The main objective of this study was to investigate whether or not geographically isolated populations of A. l. petraea differ in their responses to environmental stimuli and thus demonstrate potential for local adaptation. Under controlled environmental conditions, populations from the British Isles and Norway demonstrated the highest average growth rates whilst the lowest rates were observed in Swedish populations. Populations also exhibited significantly altered growth rates under imposed hot and cold stress conditions than in their corresponding no-stress controls. The percentage of plants that flowered was significantly higher in Norwegian populations than for those from Sweden, Iceland, and the British Isles.

Molecular techniques were employed to investigate differential gene expression in populations of A. l. petraea from Norway, Sweden, Iceland, and the British Isles, both prior to and following exposure to cold temperature stress. Extent of up-regulation of expression following exposure to chilling differed for a number of genes including CCA1, NAC2, and SKIP16. Microarray analysis identified 207 genes that were differentially expressed between two focal populations, Leitrim (Ireland) and Helin (Norway), irrespective of temperature treatment (P <0.05, fold change >2). Approximately 6% of the A. l. petraea transcriptome was responsive to acclimation whilst expression of 75 genes, many annotated as unknown function, changed following exposure to freezing.

The identified phenotypic variation is indicative of local adaptation, and populations from throughout the species’ range may thus harbour unique genetic variation. Further investigation of genes identified as important in plant responses to cold temperatures may facilitate crop improvement through GM technologies.