Minisymposium 18: Seed Biology

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Abs # M1803: Functional Characterization of the BME3 GATA Zinc Finger Protein in Arabidopsis Seed Germination

Presenter:	Liu, Po-Pu       Contact Presenter
Authors	Liu, Po-Pu  (A)   Nonogaki, Hiroyuki  (A)
Affiliations:	(A): Oregon State University
Web Site:	http://hort.oregonstate.edu/isb/

The Arabidopsis enhancer-trap lines were screened for tissue specific β-glucuronidase (GUS) expression in germinating seeds. Approximately 121 independent lines exhibited diverse tissue-specific GUS expression patterns were isolated and kept as the Seed-GUS-Expressed library. Ninety one lines showed GUS expression predominantly in the micropylar end of the seed (named BME [Blue Micropylar End] lines). One of these lines, BME3, had a T-DNA insertion site in the 5^ι upstream region of a GATA-type zinc finger transcription factor gene (termed BME3-ZF). The BME3-ZF mRNA accumulated in seeds during cold stratification, suggesting its involvement in the physiological changes which accelerate the release of dormancy. BME3-ZF was expressed just prior to that of two GA biosynthesis enzyme genes, AtGA20ox3 and AtGA3ox1 that are also induced during cold stratification. The BME3-ZF knockout plants produced seeds exhibiting deeper dormancy, which showed reduced response to cold stratification. The ungerminated knockout seeds exhibited testa rupture, but failed to penetrate the endosperm layer. Application of gibberellic acid (GA₃) rescued impaired germination of the knockout seeds without cold stratification, indicating that the normal GA signal transduction pathway is present in the knockout seeds. These results suggest that Seed-GUS-Expressed library is a useful tool to identify the critical genes for seed germination and that BME3 GATA zinc finger protein is a positive regulator of Arabidopsis seed germination.