Poster: Seed biology
Abs #
712: Screening of Arabidopsis enhancer-trap lines for seed germination-associated genes
The Arabidopsis enhancer-trap lines (Thomas Jack¡¯s population, CS31086) from Arabidopsis Biological Resource Center were screened for β-glucuronidase (GUS) expression in imbibed seeds in order to identify and characterize seed germination-associated genes. GUS staining focused on the stages between testa and endosperm ruptures turned out to be efficient to detect GUS expression in germinating seeds. Based on preliminary results, Arabidopsis seed testa is likely impermeable to the GUS substrate and needs to be opened for the substrate to reach the endosperm and the embryo. After 1 d pre-chilling at 4¡ãC and 22 h incubation at 22¡ãC, approximately 50 seeds from each pool were transferred to GUS substrate solution. Out of 1,130 pools of 10 lines examined, 147 positive pools that showed GUS expression in germinating and germinated seeds were identified. GUS activity expressed in seeds was generally strong and readily detected under a dissection microscope. Diverse tissue-specific GUS expression patterns, such as radicle-, hypocotyls- and cotyledon-specific expressions, were detected in imbibed seeds during and following germination. GUS expression specific to the micropylar region was a predominant pattern and detected in 91 lines out of 147, indicating that the micropylar region of Arabidopsis seed is selectively activated during germination, which is consistent with the information obtained from tomato seed. Approximately 4,500 Arabidopsis plants are currently being grown in the greenhouse. Individual enhancer-trap lines are being identified by staining the next generation of seeds for GUS expression. The T-DNA insertion sites in individual lines are being analyzed by genome-walking PCR to identify seed-germination-associated genes.
