Plant Science 185–186 (2012) 331–339 Contents lists available at SciVerse ScienceDirect Plant Science journal homepage: www.elsevier.com/locate/plantsci Physiological and biochemical changes of CBF3 transgenic oat in response to salinity stress Hesham Oraby a,c,∗ , Rashid Ahmad b a Department of Plant Science, Faculty of Agriculture and Food Science, Laval University, Quebec, QC, Canada b Department of Crop Physiology, University of Agriculture, Faisalabad, Pakistan c Department of Crop Science, Faculty of Agriculture, Zagazig University, Zagazig, Egypt article info Article history: Received 25 October 2011 Received in revised form 6 January 2012 Accepted 6 January 2012 Available online 14 January 2012 Keywords: CBF3 rd29A promoter Physiological traits Transgenic Salinity stress abstract Salinity is a major abiotic constraint affecting oat productivity. Several physiological and biochemical traits have been found to be related to yield maintenance under salinity. The impact of introducing the Arabidopsis CBF3 gene controlled by the rd29A stress-inducible promoter in T 2 transgenic oat on salinity tolerance and associated physiological changes were studied. Compared with the non-transgenic control, transgenic T 2 plants exhibited greater growth and showed significant maintenance of leaf area, relative water content, chlorophyll content, photosynthetic and transpiration rates as well as increased levels of proline and soluble sugars under high salt stress. These physiological changes delayed leaf-wilting symptoms, increased tolerance and reduced yield loss. At a salinity stress level of 100 mM, the CBF3- overexpressing transgenic oat showed a yield loss of 4–11% compared with >56% for the non-transgenic control. These results demonstrate that stress-inducible over-expression of CBF3 may have the potential to enhance abiotic stress tolerance in oat. © 2012 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Plant development, growth and productivity are adversely influ- enced by environmental abiotic stresses such as salinity [1]. The excess of salts in soil or irrigation water exposes plant functions and metabolism to severe stress [2]. These conditions significantly decrease the yield of current crop species and limit their expansion, and constraint the introduction of new crop species [3]. Plant acclimation to salinity stress involves cascades of tran- scriptional control and genetic regulations at different molecular levels throughout the plant life cycle [4]. These changes in gene expression mediate a wide range of biochemical and physiological processes necessary to re-establish cellular homeostasis [5]. Recently, significant improvements in salinity tolerance have been achieved in different crops through traditional breeding [6]. How- ever, progress remains slow due to many factors such as: (i) the complexity of the trait and inefficiency of selection methods, (ii) the limited information available regarding the inheritance of tolerance and selection indices, (iii) the lack of genetic variability in the crop’s gene pool, (iv) the focus on improving yield and quality and (v) ∗ Corresponding author at: Department of Plant Science, Faculty of Agriculture and Food Science, Pavillon de l’Envirotron, Laval University, Quebec, QC, Canada. Tel.: +1 418 717 2174; fax: +1 418 656 3515. E-mail address: Hesham.Oraby@fsaa.ulaval.ca (H. Oraby). the inadequate understanding of genotype and stress interactions [5,7]. A promising approach for augmenting genetic improvement of stress tolerance involves the activation of stress-inducible signal transduction pathways in transgenic plants [8]. The down- stream genes encode structural proteins or enzymes involved in the synthesis of metabolites that trigger different physiolog- ical responses [8,9]. A number of regulatory genes, associated with stress tolerance response, to be used for genetic transfor- mation have been identified including the Arabidopsis CBF/DREB (cold-binding factor/dehydration responsive element binding) transcriptional factors family. These transcription factors contain an AP2/ERF (APETALA2/Etylen Responsive element binding Factor) DNA-binding domain that recognizes dehydration responsive/C- repeat (DRE/CRT) elements. These elements are present in many COR genes that regulate gene expression in response to abiotic stresses [10]. Overexpression of CBF3 under the control of the CaMV 35S promoter was found to increase tolerance to drought, salinity, and freezing stresses. However, phenotypic abnormalities were apparent under normal growth conditions [11]. Therefore, the use of rd29A stress-inducible promoter was found to increase stress tolerance and minimize the negative effects of the CBF family including CBF3 in different heterologous systems such as tobacco [12], sugarcane [13], maize [14], potato [15], peanut [16] and tall fescue [17]. Oat is an important cereal crop used in human and animal diets [18] as it has high contents of both phytochemicals and fibers 0168-9452/$ – see front matter © 2012 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.plantsci.2012.01.003