Marker gene expression driven by the maize ubiquitin promoter in transgenic wheat

Selecting a promoter for driving transgene expression is one of the most im portant factors to consider in a transformation project. Information about the native regulation of the promoter activity is important, but it is also necessary to consider how that activity will be affected when integrated i nto the genome of the transformed plants. Study of a promoter performance i n individually transformed lines provides useful information in this area. The maize ubiquitin 1 (Ubi-l) promoter has been widely used to drive consti tutive transgene expression in monocotyledonous plants. However, lack of da ta on its activity in individual transformed wheat lines constitutes a gap in the understanding and predictability of this promoter's performance. In this paper, we began addressing this problem by examining the expression of the marker gene uidA, coding for beta-glucuronidase (GUS), under the contr ol of the maize Ubi-l promoter in individual transgenic wheat (Triticum aes tivum L.) lines from different wheat varieties. The expression of uidA driv en by this promoter depended to a great extent on the specific transformati on event. Whilst expression was strong and constitutive in all tissues in s ome of the lines analysed, there were also transgenic lines in which GUS ac tivity was restricted to only a few tissues. In general the maize Ubi-l pro moter had strong activity in young, metabolically active tissues and in pol len grains.