ARS | Publication request: The drought response transcriptome of cotton

Submitted to: World Cotton Research Conference Proceedings
Publication Type: Proceedings/Symposium
Publication Acceptance Date: September 10, 2007
Publication Date: September 14, 2007
Citation: Payton, P.R., Kebede, H., Wright, R., Allen, R. 2007. The drought response transcriptome of cotton. World Cotton Research Conference Proceedings.

Technical Abstract: Our long-term goal is to explore the regulatory networks that control the expression of stress responsive genes. The principal aim of this study was to identify cotton genes implicated in water-deficit stress by comparing information generated by functional genomics and bioinformatics approaches. We examined transcript-level responses to water-deficit stress in cotton leaves and roots using the second-generation cotton oligonucleotide microarrays. Plants were subjected to slow-onset water-deficit and monitored for leaf water potential and photosynthetic response. At the time of leaf and root tissue harvest, leaf water potentials averaged -8.7 Bars (+ 0.37 SE) for fully irrigated control plants and -23.1 Bars (+ 0.28 SE) for stressed plants, and leaf photosynthetic rates had decreased approximately to 60% of the rates seen in the irrigated controls. Gene expression profiling experiments were carried out using the second-generation cotton oligonucleotide microarray. The array is composed of 12,006 oligonucleotides derived from an assembly of more than 180,000 Gossypium ESTs sequenced from 30 cDNA libraries (www.cottonevolution.info/microarray). Transcript profiling revealed 1401 transcripts identified as drought responsive in root and leaf tissues. A total of 678 transcripts were classified as drought-induced and compared to 674 drought repressed transcripts in root and/or leaf. While significantly larger numbers of drought-responsive genes were identified in leaf compared to root, 1012 and 444 respectively, only 99 genes showed similar patterns of stress expression in both tissues. Additionally, 49 transcripts showed reciprocal expression patterns in root and leaf (11 transcripts induced in root, but repressed in leaf; 38 transcripts induced in leaf but repressed in root). A total of 158 (84 drought-induced and 74 drought-repressed) genes were electronically mapped, of which 22 (8 induced and 14 repressed) genes co-localized with a know stress-related QTL. A complete presentation and discussion of our findings, including the association of these candidate genes with QTLs that influence plant productivity and fiber quality in response to drought stress conditions will be presented at this meeting.