Submitted to: Functional and Integrative Genomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/25/2005
Publication Date: 2/1/2006
Citation: Walia, H., Wilson, C., Wahid, A., Condamine, P., Cui, X., Close, T.J. 2006. Expression analysis of barley (Hordeum vulgare L.) during salinity stress. Functional and Integrative Genomics. Vol 6: 143-156 Interpretive Summary: Salinity is one of the major obstacles to increasing crop productivity. Barley (hordeum vulgare L.) is considered salt tolerant. Barley’s salt tolerance has been of interest for a long time and a considerable body of physiological, genetic, and cytogenetic data have been established. However, recent advances has now led to characterization of salinity stress in plants on a molecular level to identify genes. Large-scale approaches including microarrays and differential displays have identified genes involved in the plant’s response to salinity stress. Recently, an oligonucleotide array, the Barley 1 GeneChip, became publicly available. In this work, we emoplyed the Barley 1 GeneChip to investigate the transcriptional response of barley cv. Morex to a gradually imposed salinity stress at the salt-sensitive seedling stage of barley. We focused on the ion-specific effects of salinity on gene expression as opposed to osmotic shock. We found a comparable number of probe sets that increased and decreased in response to salinity. One important finding was the increase of genes that are believed to respond to the plant hormone, jasmonic acid. A large number of genes that also respond to other stresses including heat, drought, and low temperature were also found to respond to salinity stress. Additionally, we found that osmoprotection to be an early response of barley to salinity stress. Finally, when we compared our results with two other reports investigating gene expression of barley under salinity stress, we found very few genes in common. Our findings should assist the plant breeder in selecting more salt tolerant crops.
Technical Abstract: Barley (Hordeum vulgare L.) is a salt-tolerant crop species with considerable economic importance in salinity-affected arid and semiarid regions of the world. In this work, barley cultivar Morex was used for transcriptional profiling during salinity stress using a microarray containing ~22,750 probe sets. The experiment was designed to target the early responses of genes to a salinity stress at seeding stage. We found a comparable number of probe sets up-regulated and down regulated in response to salinity. The differentially expressed genes were broadly characterized using gene ontology and through expression-based hierarchical clustering to identify interesting features in the data. A prominent feature of the response to salinity was the induction of genes involved in jasmonic acid biosynthesis and genes known to respond to jasmonic acid treatment. A large number of abiotic stress (heat, drought, and low temperature) related genes were also found to be responsive to salinity stress. Our results also indicate osmoprotection to be an early response of barley under salinity stress. Additionally, we compared the results of our studies with two other reports characterizing gene expression of barley under salinity stress and found very few genes in common.