Symposium IV: Sensing and responding to water

Abs # 40001: Drought Responses in Rice and Drought Effects on the Corn Root Transcriptome

Presenter:	Bohnert, Hans J, bohnerth@life.uiuc.edu
Authors	Bohnert, Hans J (A) (D)  Sharp, Robert E (B)   Hejlek, Lindsey G (B)   Poroyko, Valeriy  (A)   Fredricksen, Mark  (A)   Pazhamala-Thankappan, Lekha  (A) (F)  Spollen, William G (C)   Springer, Gordon K (C)   Davis, Georgia  (B)   Schachtman, Daniel P (E)   Katiyar, Sanjay K (A) (F)  Nguyen, Henry T (B)
Affiliations:	(A): Dept. Plant Biology & Dept. Crop Sciences, U. Illinois, Urbana, IL 61801 (B): Dept. Agronomy, U. Missouri, Columbia, MO 65211 (C): Dept. Computer Science, U. Missouri, Columbia, MO 65211 (D): W.M. Keck Center for Comparative and Functional Genomics, U. Illinois, Urbana, IL 61801 (E): Donald Danforth Plant Science Center, St. Louis. MO, 63132 (F): Dept. Biotechnol., Indira Gandhi Agricultural U., Raipur 492006, India
Web Site:	http://rootgenomics.missouri.edu/prgc/index.htm

The effect of water deficit, caused by drought, salinity or low temperature, on plants may be analyzed on different levels. We are interested in transcript and protein alterations in cereals during drought, with a focus on rice and corn. Large EST collections exist that can be analyzed for expression characteristics that distinguish species, ecotypes, and lines, and that reveal changes in transcript populations in the response to experimental manipulations. Two examples, application of microarray analysis and the diligent construction and analysis of transcript libraries, will be outlined here and applied to drought responses. A comparison of rice cultivars, parents of mapping populations, indicates significant differences in drought response timing, rather than in gene complement. Sensitive cultivars respond slowly to rapid changes in water supply. In corn, we focus on transcript populations in the primary root growth zone of seedlings under well-watered or water-deficit conditions. Physiological studies showed that the ability for root growth maintenance under water deficit is cultivar specific and ABA dependent, and that cell expansion responds differently to water deficit in distinct regions of the root tip. We analyzed 4 regions of the tip, 0-3, 3-7, 7-12, and 12-20 mm, through transcript profiling under three conditions: well-watered (WW, 5+48h combined) and water-deficit (WS05- 5h; WS48- 48h). Twelve primary libraries (3 conditions, 4 segments each) were generated such that each library carried a sequence tag for identification. After combining segmental libraries for the conditions WW, WS05, and WS48, three normalized libraries were generated and ~6,000 clones from each sequenced, resulting in >8,000 transcripts for unique genes. Comparison of the transcript profiles pinpoints population differences between WW and WS. Also, a corn root-specific SAGE library, including >150,000 tags provides the corn root complement and true abundance profile. This approach, presently augmented by additional microarray- and quantitative PCR-based transcript profiling, represents a way to merge physiological analyses with high-throughput technologies. Funded by the National Science Foundation (DBI-0211842), UIUC and MU institutional grants, Government of India, and the Rockefeller Foundation. (http://www.life.uiuc.edu/bohnert/; http://rootgenomics.missouri.edu/prgc/index.htm).