Poster: Hormones

Abs # 586: Hormone response mutants in wheat and barley

Presenter:	Strader, Lucia C, lucia_strader@yahoo.com
Authors	Strader, Lucia C (A)   Ritchie, Sian  (A)   Steber, Camille M (A) (B)
Affiliations:	(A): Washington State University (B): United States Dept. of Agriculture-Agriculture Research Service

Barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) are key grain crops. An understanding of seed dormancy and germination in these organisms is essential to controlling the agronomic traits of preharvest sprouting (due to poor dormancy), seedling emergence, and malting quality. Due to their agronomic relevance, the study of seed germination has become well developed in both barley and wheat. The plant hormone ABA is required for establishment of seed dormancy during embryo maturation, while the hormone GA is required for stimulation of alpha-amylase production and germination. This project seeks to further elucidate the role of these hormones in germination by homologues of known ABA and GA response genes in barley and wheat. We’ve identified homologues of ABI1 (ABA Insensitive1) and SLY1 (SLEEPY1), among others. These genes function in ABA-response and GA-response, respectively. In Arabidopsis, mutations in either of these genes causes a seed germination phenotype. To prove functionality of these genes in wheat, we have performed genetic screens for increased and decreased ABA sensitivity in wheat. Screening 22,520 afterripened fast-neutron mutagenized wheat seeds for lack of gemination in 5 mM ABA resulted in 89 putative era (enhanced response to ABA) mutants, 39 of which retested. Screening 7,320 dormant EMS-mutagenized wheat grains for germination in 5 mM ABA resulted in 31 putative ABI mutants, 11 of which retested for this phenotype. Barley GA-response mutants are being characterized as well. We are in the process of characterizing these mutants in terms of their homology to known signaling mutants, their germination phenotypes, and their gene expression patterns.