Academic journal article Genetics

The Association among Gene Expression Responses to Nine Abiotic Stress Treatments in Arabidopsis Thaliana

Academic journal article Genetics

The Association among Gene Expression Responses to Nine Abiotic Stress Treatments in Arabidopsis Thaliana

Article excerpt

ABSTRACT

The identification and analysis of genes exhibiting large expression responses to several different types of stress may provide insights into the functional basis of multiple stress tolerance in plant species. This study considered whole-genome transcriptional profiles from Arabidopsis thaliana root and shoot organs under nine abiotic stress conditions (cold, osmotic stress, salt, drought, genotoxic stress, ultraviolet light, oxidative stress, wounding, and high temperature) and at six different time points of stress exposure (0.5, 1, 3, 6, 12, and 24 hr). In roots, genomewide correlations between transcriptional responses to different stress treatments peaked following 1 hr of stress exposure, while in shoots, correlations tended to increase following 6 hr of stress exposure. The generality of stress responses at the transcriptional level was therefore time and organ dependent. A total of 67 genes were identified as exhibiting a statistically significant pattern of gene expression characterized by large transcriptional responses to all nine stress treatments. Most genes were identified from early to middle (1-6 hr) time points of stress exposure. Analysis of this gene set indicated that cell rescue/defense/virulence, energy, and metabolism functional classes were overrepresented, providing novel insight into the functional basis of multiple stress tolerance in Arabidopsis.

(ProQuest Information and Learning: ... denotes formulae omitted.)

THE genetic effects of environmental stress have been extensively studied from the standpoint of cellular physiology (SINGH et al. 2002; MAHALINGAM et al. 2003; CHEN and ZHU 2004), evolutionary biology (HOFFMANN and PARSONS 1991, 1997), and increasingly, biotechnology (HOLMBERG and BÜLOW 1998; KASUGA et al. 1999; WANG et al. 2003; PELLEGRINESCHI et al. 2004; DENBY and GEHRING 2005; VINOCUR and ALTMAN 2005). In plant species, environmental stress can be a large source of mortality because plants are unable to avoid environmental extremes through migration. Stress is thus a powerful force influencing the evolution of plant populations in the wild (HOFFMANN and PARSONS 1997), as well as a key factor limiting economic yield in commercially valuable species (BOYER 1982; BLUM 1988). The susceptibility of plants to environmental extremes has driven the evolution of a wide range of stress-resistance and tolerance mechanisms (SINGH et al. 2002; MAHALINGAM et al. 2003; CHEN and ZHU 2004; BOHNERT et al. 2006). In the model system Arabidopsis thaliana, the physiological basis of these resistance mechanisms has been pursued with the ultimate goal of elucidating the biochemical pathways involved in stress perception, signal transduction, and adaptive response (e.g., SEKI et al. 2001, 2002; KREPS et al. 2002; HAZEN et al. 2003; TAKAHASHI et al. 2004; LIU et al. 2005). While many stress responses appear to be specific to different forms of stress, it is clear that some stress responses are general and potentially confer tolerance to multiple types of stress (CHINNUSAMY et al. 2004; KIM et al. 2004). The genes associated with these general stress responses may yield insight into biochemical networks underlying stress resistance and may provide targets for stress-resistance engineering in plant species.

The functional basis of multiple-stress tolerance has been explained from both mechanistic and energetic perspectives. The mechanistic viewpoint has largely emerged from studies focusing on plant model systems, in which similarities between cellular responses to different types of stress have been explained in terms of the shared effects of different stress treatments on cellular water potential (VERSLUES et al. 2006). This common effect has frequently been cited to explain associations found among cold, drought, and salinity stress responses in Arabidopsis and other plant species (e.g., MUNNS 2002; DENBY and GEHRING 2005; VERSLUES et al. 2006). The energetic viewpoint has attempted to account for cross-tolerance mechanisms more broadly in terms of the common effect that different stress conditions have on energy allocation (HOFFMANN and PARSONS 1991, Chap. …

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