Interference 103,579
reverse orientation, or gene sequences including an upstream
promoter sequence and a fragment substantially larger in size
than SEQ ID Nos. 1, 2 and 3 in reverse orientation are, in
general, not useful to substantially inhibit expression of
PGBSS in potato plants, i.e., to transform potato plants to
suppress amylose formation, and not part of Hofvander’s
invention (HR 278-279; emphasis added):
In potato, experiments have previously been made
to inhibit the synthesis of the granule-bound starch
synthase (GBSS protein) with an antisense construct
corresponding to the gene coding for GBSS (this gene is
hereafter called the “GBSS gene”). Hergersberg (1988)
[(VDX1)] describes a method by which a cDNA clone for the
GBSS gene in potato has been isolated by means of a cDNA
clone for the wx+ gene in maize. An antisense construct
based on the entire cDNA clone was transferred to leaf
discs of potato by means of Agrobacterium tumefaciens.
In microtubers induced in vitro from regenerated potato
sprouts, a varying and very weak reduction of the amylose
content was observed and shown in a diagram. A complete
characterization of the GBSS gene is not provided.
The gene for the GBSS protein in potato has been
further characterised [sic] in that a genomic wx+ clone
was examined by restriction analysis. However, the DNA
sequence of the clone has not been determined (Visser
et al, 1989).
Further experiments with an antisense construct
corresponding to the GBSS gene in potato have been
reported. The antisense construct which is based
on a cDNA clone together with CaMV 35S promoter has
been transformed by means of Agrobacterium rhizogenes.
According to information, the transformation resulted
in a lower amylose content in the potato, but no values
have been accounted for (Flavell, 1990).
None of the methods used so far for genetically
engineered modification of potato has resulted in potato
with practically no amylose-type starch.
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