UC San Diego

The MADS-box gene FRUITFULL (FUL) plays a critical role in Arabidopsis thaliana fruit development after fertilization, particularly in the valves. While research has uncovered a number of genes that function upstream of FUL, there is little information on how FUL is directly regulated. To address this, the FUL promoter was studied in order to isolate the cis-acting regulatory regions that are required for FUL transcription. A 3.9 kb long promoter upstream the FUL genomic sequence was demonstrated to direct the expression of the [Beta]-glucuronidase (GUS) reporter gene in a pattern that mimicked the FUL expression pattern previously reported in mRNA in situ hybridization studies and ful-1 DsE enhancer trap lines. In a "promoter-bashing" study, we identified a 682 bp long region within this 3.9 kb promoter that contained at least one cis-element required for transcriptional activation of FUL in the valves. Site-directed mutagenesis revealed that a CArG box in this aforementioned region was required for the repression of ectopic transcription in the ovules but was not required for expression in the valve cells. Further studies will precisely identify the cis-element(s) in this regulatory region that positively regulate FUL transcription in the valves. Additionally, our data showed that the 3' region of the 3.9 kb promoter was required for FUL-like expression in the inflorescence stem