The arcelin-5 gene of Phaseolus vulgaris directs high seed-specific expression in transgenic Phaseolus acutifolius and Arabidopsis plants

The regulatory sequences of many genes encoding seed storage proteins have been used to drive seed-specific expression of a variety of proteins in tra nsgenic plants. Because the levels at which these transgene-derived protein s accumulate are generally quite low, we investigated the utility of the ar celin-5 regulatory sequences in obtaining high seed-specific expression in transgenic plants. Arcelin-5 is an abundant seed protein found in some wild common bean (Phaseolus vulgaris L.) genotypes. Seeds of Arabidopsis and Te pary bean (Phaseolus acutifolius A. Gray) plants transformed with arcelin-5 gene constructs synthesized arcelin-5 to levels of 15% and 25% of the tota l protein content, respectively. To our knowledge, such high expression lev els directed by a transgene have not been reported before. The transgenic p lants also showed low plant-to-plant variation in arcelin expression. Compl ex transgene integration patterns, which often result in gene silencing eff ects, were not associated with reduced arcelin-5 expression. High transgene expression was the result of high mRNA steady-state levels and was restric ted to seeds. This indicates that all requirements for high seed-specific e xpression are cis elements present in the cloned genomic arcelin-5 sequence and trans-acting factors that are available in Arabidopsis and Phaseolus s pp., and thus probably in most dicotyledonous plants.