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.