Submitted to: Biotechnology Letters
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/8/2010
Publication Date: 12/28/2010
Citation: Payton, P.R., Kottapalli, K.R., Kebede, H.A., Mahan, J.R., Wright, R.J., Allen, R.D. 2010. Examining the drought stress transcriptome in cotton leaf and root tissue. Biotechnology Letters. 33:821-828. Interpretive Summary: Although cotton exhibits moderately high tolerance during vegetative development, water-deficit stress is one of the major limiting factors in its production. The potential to identify key traits that limit yield under abiotic stress conditions hinges upon our understanding of the responses at both the physiological and molecular levels and integrating these responses with whole-plant phenotypes. Recent advances in molecular biology have provided powerful tools for the genetic dissection of abiotic stress responses in crop plants. This study employs DNA microarray technology to investigate the molecular response to drought stress in cotton root and leaf tissue and identify genes involved in the complex pathways affected by this stress. We identified 2079 genes that show distinct responses to water deficit stress. Of these, only 172 show similar responses in both leaf and root, the vast majority of stress-responsive genes appear to be tissue-specific, in terms of the their expression under stress and suggest a unique role in either leaf or root. The outcome of this research is a collection of candidate genes and metabolic pathways that will be tested as mechanisms for altering the response to water-deficit stress and ultimately the tolerance of cotton to water-deficit stress.
Technical Abstract: Lint yield and quality in cotton is greatly affected by water-deficit stress. The principal aim of this study was to identify cotton genes associated metabolic pathways involved in the water-deficit stress response. Gene expression profiles were developed for leaf and root tissues subjected to slow-onset water deficit under controlled, glasshouse conditions. The stress was characterized by leaf water potential of -23.1 Bars for stressed tissue compared to -8.7 Bars for fully-irrigated control plants and a corresponding decrease in net photosynthesis to approximately 60% of the rates seen in the irrigated controls (30.3 + 4.7 µmol CO2 m-2 s-1 compared to 17.8 + 5.9 µmol CO2 m-2 s-1). Profiling experiments revealed 2079 stress-responsive transcripts, 854 classified as stress-induced and 1157 stress-repressed in root and/or leaf. Interestingly, the majority of stress-responsive transcripts appear to have tissue-specific expression patterns and only 172 genes showed similar patterns of stress responsive expression in both tissues. A variety of putative metabolic and regulatory pathway were identified using MapMan software and the potential targets for candidate gene selection and ectopic expression to alter these pathways and responses are discussed.