Cj. Sarah et al., DISTINCT CIS-ACTING ELEMENTS DIRECT THE GERMINATION AND SUGAR RESPONSES OF THE CUCUMBER MALATE SYNTHASE GENE, MGG. Molecular & general genetics, 250(2), 1996, pp. 153-161
The malate synthase gene (ms) promoter in cucumber (Cucumis sativus L.
) was investigated with the aim of distinguishing DNA sequences mediat
ing regulation of gene expression by sugar, and expression following s
eed germination. Promoter deletions were constructed and their ability
to direct expression of the beta-glucuronidase (gus) reporter gene wa
s investigated in transgenic Nicotiana plumbaginifolia. Gene expressio
n was assayed in germinating seeds and developing seedlings (the germi
nation response) and in seedlings transferred from light into darkness
with and without sucrose (the sugar response). As progressively more
of the promoter was deleted from the 5' end, first the sugar response
and then the germination response was lost. Thus, distinct regions of
the promoter are required for carbohydrate control and for regulation
of gene expression in response to germination. Sequence comparisons of
the ms promoter with that of the isocitrate lyase gene (icl) of cucum
ber have previously identified four IMH (ICL-MS Homology) sequences. O
ne such sequence, IMH2, is shown here to be implicated in the sugar re
sponse of the ms gene. The 17 bp sequence, which when deleted from the
ms gene results in loss of the germination response, contains a 14 bp
sequence which is similar to a sequence in the icl promoter, which we
refer to as IMH5. Furthermore, this sequence has similarity with amdI
9-like sequences in filamentous fungi, which confer facB-mediated acet
ate inducibility on several genes, including those encoding ICL and MS
.