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The above promoters were found to be Inure efficient In dlcots a?d there was a
.- -
distinguished interest for finding out the promoters for monocots. In the early studies with
/-
rice (Shimanloto et al., 1989) the CaMV 35s promoter was used to activate tile selective
7
and repotter genes. However, it was found that this promoter was more efficient in dicots.
Conlbination of this promoter with other pro:lioter segments and introns were even tried.
This concept was followed by the wage of ccieul alcol~ul dehydrogenw I (Adlil) gene
- +...- .-
(Callis et dl., 1987; Kyozuka ct al., 1990). A silliilar approacll to integrate the first intron of
the 3hru1iki.11 I gene of maize was also followed in cereal tratlsformat~on (Mass et al.,
1991), but I: becatue less popular in the subsequent years. Rice actin gene pro~l~oter (Acll)
- .
was found to be even nlo1.e potent than the above two (Zliang ct al., 1991). This pronioter
showed more or less similar potency as that of Ettiu pron~otcr tllat is a recombii~allt
promoter cotltaining a ti-ul~cated Adlil~n?_oter with other elements (Last et a]., 1991). The
--
curretlt most effective promoter is tile Ubiyuiiiii I (Ubii) of n~aize (Clrrislcnseit et al.,
1992). Tii~a proilioter was used successfully to tlnnsfornl !\,\.heat (Weeds el al., 1993)
barley (Wan and Lemaux, 1994) and rice (Toki et nl., 1992). Another pronloter of tile rice
Aldviure P (Aidl') gene was ibund to be one of tile bctter alternat~ve (Kagaya et al., 1995).
Tcnrii~zrrlars: Knowledge of the ele~lleiits for geilc expression 1s as important as the
promoters. It is considered that fundamentally n1RN.A is stable unless destabilizing motifs
are involved. Specific examplcs of the studles that handled the polyadenylation signals in
plants are investigations of Mogen ct al. (1990). 1:otiinie et al. (1994) studied the essence
of the terminator regions and impact of 3'-end ~.cgions on the level of gene expression of
octopine syntliasc gene and otllcr gene constructs was studied by lngelbrecht et al. (1989).
Hence, the usage of tern~inator region at [lie 3' end of tile transgene was found to be