Promoter analysis of seed storage protein genes from Canavalia gladiata D.C

Abstract

A number of A/T-rich sequences and a CATGCAT/A sequence are contained in the 5'-upstream regions of the genes encoding concanavalin A (Con A) and canavalin, two major seed storage proteins of Canavalia gladiata D.C. To study the role of these sequences in the seed-specific gene expression, we constructed 5'-deletion mutants and examined the transient expression of beta-glucuronidase reporter gene by particle bombardment and the stable expression by Agrobacterium-mediated transformation of tobacco plants. Positive regulatory elements were located in the -894/-602 and -602/-74 regions of the Con A gene, and in the -428/-376, -281/-155 and -155/-50 regions of the canavalin gene. In addition, the results suggested that the A/T-rich sequences in the 5'-upstream region of the Con A gene play a role in transcriptional activation, but that those of the canavalin gene have little effect on the gene expression. The CATGCAT/A sequence was not sufficient by itself for high levels of expression of both the Con A and canavalin genes. The canavalin polypeptide amounted to about 1% of the total extractable protein in the transgenic tobacco seeds, but the Con A polypeptide was not detected in the extractable protein.