title: Fitness benefits and costs of cold acclimation in Arabidopsis thaliana.
abstract: Abstract When resources are limited, there is a trade-off between growth/reproduction and stress defense in plants. Most temperate plant species, including Arabidopsis thaliana, can enhance freezing tolerance through cold acclimation at low but nonfreezing temperatures. Induction of the cold acclimation pathway should be beneficial in environments where plants frequently encounter freezing stress, but it might represent a cost in environments where freezing events are rare. In A. thaliana, induction of the cold acclimation pathway critically involves a small subfamily of genes known as the CBFs. Here we test for a cost of cold acclimation by utilizing (1) natural accessions of A. thaliana that originate from different regions of the species' native range and that have experienced different patterns of historical selection on their CBF genes and (2) transgenic CBF overexpression and T-DNA insertion (knockdown/knockout) lines. While benefits of cold acclimation in the presence of freezing stress were confirmed, no cost of cold acclimation was detected in the absence of freezing stress. These findings suggest that cold acclimation is unlikely to be selected against in warmer environments and that naturally occurring mutations disrupting CBF function in the southern part of the species range are likely to be selectively neutral. An unanticipated finding was that cold acclimation in the absence of a subsequent freezing stress resulted in increased fruit production, that is, fitness.
authors.affiliation: Division of Biology, Kansas State University, Manhattan, Kansas 66506, USA. yzhen@princeton.edu
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhen
authors.forename: Preeti
authors.initials: P
authors.lastname: Dhakal
authors.forename: Mark C
authors.initials: MC
authors.lastname: Ungerer
mesh_terms: D000064:Acclimatization; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D003080:Cold Temperature; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D056084:Genetic Fitness; D030821:Plants, Genetically Modified / Q000502:physiology; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; C104387:CBF1 protein, Arabidopsis; C118228:CBF2 protein, Arabidopsis; D004269:DNA, Bacterial; C114578:DREB1A protein, Arabidopsis; C036483:T-DNA; D015534:Trans-Activators; D014157:Transcription Factors