Poster: Seed biology

Abs # 713: Tissue-specific expression of a protein phosphatase 2C in germinated Arabidopsis seeds

Presenter:	Homrichhausen, Tanja M., homricht@onid.orst.edu
Authors	Homrichhausen, Tanja M. (A)   Liu, Po-Pu  (B)   Nonogaki, Hiroyuki  (B)
Affiliations:	(A): Department of Chemical Engineering, Oregon State University (B): Department of Horticulture, Oregon State University

An Arabidopsis enhancer-trap line (TMH1) which showed root-specific β-glucuronidase (GUS) expression in germinated seeds was characterized. GUS expression in this line occurred exclusively in the elongation zone of the radicle immediately after its emergence and disappeared during the post-germinative stages, indicating that the trapped gene may be involved in early root development before seedling establishment. Genome walking PCR was performed to identify the T-DNA insertion site. An approximate 0.7 kb DNA fragment was amplified from genomic DNA of TMH1, sequenced, and was found to contain the T-DNA right border. The DNA sequence flanking the T-DNA right border was analyzed and predicted to be part of genomic DNA sequence in the Arabidopsis chromosome 5. The putative insertion site was predicted to be at the intergenic region between At5g02750 (zinc finger protein) and At5g02760 (protein phosphatase 2C). RT-PCR was conducted to examine potential mRNA expression of these two genes. Total RNA was prepared from wildtype Arabidopsis seeds imbibed for 36 h and subjected to RT-PCR using At5g02750- and At5g02760-specific primers. The predicted size product (1.1 kb) was amplified for At5g02760, and no product was obtained for At5g02750. Both sets of primers amplified the predicted size DNA fragments from wildtype Arabidopsis genomic DNA (0.7 kb and 1.4 kb for At5g02750 and At5g02760, respectively). These results indicate that At5g02760 gene is actually expressed in germinated Arabidopsis seeds and suggest that a protein phosphatase 2C is involved in early root development before seedling establishment