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Title: Large scale q-PCR reveals maize transcription factors that are regulated under water deficit in a tissue-specific manner

item Cho, In-Jeong
item Oliver, Melvin

Submitted to: Gordon Research Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 8/12/2008
Publication Date: 9/7/2008
Citation: Cho, I., Trupti, J., Gyan, S., Dong, X., Leonard, H., Oliver, M.J. 2008. Large scale q-PCR reveals maize transcription factors that are regulated under water deficit in a tissue-specific manner. Gordon Research Conference: Salt and Water Stressing Plants, September 7-12, 2008, Big Sky, Montana. 2008 CDROM.

Interpretive Summary:

Technical Abstract: Water deficit stress is a major component of agricultural drought events and contributes greatly to yield loss in all crops. Genetic modification to improve water deficit tolerance is an obvious strategy to mitigate this problem and an understanding of the mechanism of adaptation to water deficit is critical to success. Maize, apart from being a major crop, is an ideal model for research into this area, offering a wealth of genetic and genomic information and tools. Under water deficit, roots and leaves undergo various processes to maintain water balance, many of which are driven by alterations in gene expression. We have chosen to concentrate our efforts on the water deficit response of genes that encode transcription factors (TFs), which are often early responders and affect a broad range of genes and processes. Our initial approach was to identify TFs that are both spatially and temporally regulated under water deficit in maize using high throughput quantitative PCR. We chose a well-characterized model system that allows us to tightly control the water deficit that the plant experiences: maize seedlings exposed to a water deficit (-0.3 MPa,) in a controlled environment. We sampled seedling structures over a time course of exposure, 5h, 26h, and 44h after the initiation of the stress. We targeted all of the TFs in maize that were homologous to the complete TF complement of rice as our starting point, a total of 384 TFs. Of the total TF collection, 235 exhibited expression regulation under the water deficit treatment. The TFs were categorized into 16 families including ABI/VP1, AP2/EREBP, bZIP, MADS, MYB, and NAC. Each tissue, root-tip, elongating root, mesocotyl, hypocotyl, coleoptile, and true leaves, differed in both the number of TFs that responded to the treatment and which individual TF responded. However, for the majority of the responsive TFs, expression was initiated at 5h, peaking at 26h, and declining in expression after 44h. Importantly the data indicates tissue-specific regulation of TF encoding genes in seedlings under a precise water deficit. These data form the basis of our ongoing attempts to gain a full understanding of how maize responds to drought and move us toward our ultimate goal to design reasoned strategies for crop improvement for drought tolerance.