title: Acquisition of freezing tolerance in Arabidopsis and two contrasting ecotypes of the extremophile Eutrema salsugineum (Thellungiella salsuginea).
abstract: Eutrema salsugineum (Thellungiella salsuginea) is an extremophile, a close relative of Arabidopsis, but possessing much higher constitutive levels of tolerance to abiotic stress. This study aimed to characterize the freezing tolerance of Arabidopsis (Columbia ecotype) and two ecotypes of Eutrema (Yukon and Shandong) isolated from contrasting geographical locations. Under our growth conditions, maximal freezing tolerance was observed after two- and three-weeks of cold acclimation for Arabidopsis and Eutrema, respectively. The ecotypes of Eutrema and Arabidopsis do not differ in their constitutive level of freezing tolerance or short-term cold acclimation capacity. However Eutrema remarkably outperforms Arabidopsis in long-term acclimation capacity suggesting a wider phenotypic plasticity for the trait of freezing tolerance. The combination of drought treatment and one-week of cold acclimation was more effective than long-term cold acclimation in achieving maximum levels of freezing tolerance in Eutrema, but not Arabidopsis. Furthermore, it was demonstrated growth conditions, particularly irradiance, are determinates of the level of freezing tolerance attained during cold acclimation suggesting a role for photosynthetic processes in adaptive stress responses.
authors.affiliation: Department of Plant Sciences, University of Saskatchewan, Saskatoon SK S7N 5A8, Canada.
authors.forename: Nityananda
authors.initials: N
authors.lastname: Khanal
authors.affiliation: Department of Biology, University of Waterloo, Waterloo ON N2L 3G1, Canada.
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Moffatt
authors.affiliation: Department of Plant Sciences, University of Saskatchewan, Saskatoon SK S7N 5A8, Canada; Department of Biochemistry, University of Saskatchewan, Saskatoon SK S7N 5E5, Canada. Electronic address: gr.gray@usask.ca.
authors.forename: Gordon R
authors.initials: GR
authors.lastname: Gray
mesh_terms: D000222:Adaptation, Physiological / Q000528:radiation effects; D017360:Arabidopsis / Q000254:growth & development / Q000502:physiology* / Q000528:radiation effects; D019607:Brassicaceae / Q000502:physiology* / Q000528:radiation effects; D060146:Ecotype; D005615:Freezing; D008027:Light; D045332:Photosystem II Protein Complex / Q000378:metabolism; D013312:Stress, Physiological / Q000528:radiation effects; D013696:Temperature
chemical_list: D045332:Photosystem II Protein Complex
keywords: Adaptive (phenotypic) plasticity; Arabidopsis; Cold acclimation; Eutrema salsugineum; Freezing tolerance