Expression patterns of a putative homolog of AGAMOUS, STAG1, from strawberry

Abstract

MADS box genes function to regulate vegetative, floral, and fruit development in plants. Here we characterize the expression pattern of a MADS box gene from strawberry ( Fragaria× ananassa), designated STAG1. Sequence analysis revealed that STAG1 shared 68–91% amino acid sequence identity to AGAMOUS homologs from a variety of plant species. STAG1 transcripts were detected in stamens, carpels, and developing fruit. In situ hybridization revealed that STAG1 mRNA expression was restricted to the endothelium and the vascular bundles connecting the achenes to the inner part of the receptacle and was not evident in the receptacle of the fruit. Analysis of the expression of a GUS marker gene driven by the STAG1 promoter showed that during floral development, STAG1 was active in stamens, the base of the receptacle and the petals, and in the central pith and vascular tissue. During the ripening stage of fruit development, STAG1 activity was detected in achenes, pith cells, and cortical cells. Sequence analysis and expression patterns indicate that STAG1 is an AGAMOUS homolog of strawberry.