Spatial distribution of transcript changes in the maize primary root elongation zone at low water potential

Authors

William G. Spollen, University of Missouri- ColumbiaFollow
Wenjing Tao, University of Missouri- ColumbiaFollow
Babu Valliyodan, University of Missouri- ColumbiaFollow
Kegui Chen, University of Missouri- ColumbiaFollow
Lindsey G. Hejlek, University of Missouri- ColumbiaFollow
Jong-Joo Kim, University of Arizona-TucsonFollow
Mary E. LeNoble, University of Missouri- ColumbiaFollow
Jinming Zhu, University of Missouri- ColumbiaFollow
Hans J. Bohnert, University of Illinois at Urbana-ChampaignFollow
David Henderson, University of Arizona-TucsonFollow
Daniel P. Schachtman, University of Nebraska-LincolnFollow
Georgia E. Davis, University of Missouri- ColumbiaFollow
Gordon K. Springer, University of Missouri- ColumbiaFollow
Robert E. Sharp, University of Missouri- ColumbiaFollow
Henry T. Nguyen, University of Missouri- ColumbiaFollow

Date of this Version

4-2008

Citation

BMC Plant Biology 2008, 8:32 doi:10.1186/1471-2229-8-32

Abstract

Background: Previous work showed that the maize primary root adapts to low Ψ_w (-1.6 MPa) by maintaining longitudinal expansion in the apical 3 mm (region 1), whereas in the adjacent 4 mm (region 2) longitudinal expansion reaches a maximum in well-watered roots but is progressively inhibited at low Ψ_w. To identify mechanisms that determine these responses to low Ψ_w, transcript expression was profiled in these regions of water-stressed and well-watered roots. In addition, comparison between region 2 of water-stressed roots and the zone of growth deceleration in well-watered roots (region 3) distinguished stress-responsive genes in region 2 from those involved in cell maturation.

Results: Responses of gene expression to water stress in regions 1 and 2 were largely distinct. The largest functional categories of differentially expressed transcripts were reactive oxygen species and carbon metabolism in region 1, and membrane transport in region 2. Transcripts controlling sucrose hydrolysis distinguished well-watered and water-stressed states (invertase vs. sucrose synthase), and changes in expression of transcripts for starch synthesis indicated further alteration in carbon metabolism under water deficit. A role for inositols in the stress response was suggested, as was control of proline metabolism. Increased expression of transcripts for wall-loosening proteins in region 1, and for elements of ABA and ethylene signaling were also indicated in the response to water deficit.

Conclusion: The analysis indicates that fundamentally different signaling and metabolic response mechanisms are involved in the response to water stress in different regions of the maize primary root elongation zone.