ARS | Publication request: ABA AND GA SIGNALING, BRIDGING THE GAP BETWEEN WHEAT AND ARABIDOPSIS

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 1, 2007
Publication Date: September 12, 2007
Citation: Steber, C.M., Schramm, E., Abellera, J., Strader, L.C. 2007. Aba and ga signaling, bridging the gap between wheat and arabidopsis. Translational Seed Biology: From Model Systems to Crop Improvement, UC Davis, CA, Sept. 12-20. Invited Presentation.

Technical Abstract: Wheat is subject to problems with preharvest sprouting (PHS) on the mother plant when cool moist conditions persist close to the time of harvest. This problem is one barrier to the adoption of hard white wheat varieties as a new market class in the U.S. It is believed that problems with PHS are due to lack of grain dormancy resulting mainly from lack of grain dormancy (McKibbin et al, 2002). The long term goal is to use altered ABA and GA signaling in wheat to control problems with poor dormancy and preharvest sprouting (PHS). ABA is needed to set up seed dormancy and embryo dessication tolerance during embryo maturation, and stimulate storage of nutrients. ABA also inhibits germination of mature seeds and stimulates tolerance to drought stress. GA stimulates seed germination and is needed for the breakdown of barrier tissues and mobilization of stored nutrients such as the induction of alpha-amylase for the mobilization of starch in cereals. A screen for wheat mutants with altered response to ABA in seed germination has been used as a first step to analyzing the effect of ABA sensitivity on grain dormancy. Mutants have been characterized for changes in ABA dose-response. Mutants have been identified both that appear to show an ABA-hypersensitive dose-response and that show a general increase in embryo dormancy. In addition, ABA hypersensitive seed germination appears to correspond to increased vegetative drought tolerance due to increased sensitivity to ABA in stomatal closure.