New Zealand Journal of Crop and Horticultural Science abstracts
Transformation of potato (Solanum tuberosum) cultivars with a
cry1Ac9 gene confers resistance to potato tuber moth (Phthorimaea
operculella)
M. M. Davidson1,2
M. F. G. Takla1,2
J. M. E. Jacobs1
R. C. Butler1
S. D. Wratten2
A. J. Conner1,2
1New Zealand Institute for Crop & Food
Research Limited
Private Bag 4704
Christchurch, New Zealand
2National Centre for Advanced Bio-Protection
Technologies
P.O. Box 84, Lincoln University
Canterbury, New Zealand
Abstract Eight potato (Solanum tuberosum) cultivars
were transformed with a modified cry1Ac9 gene under the transcriptional
control of the CaMV 35S promoter using Agrobacterium-mediated transformation
with a nptII gene conferring kanamycin resistance as a selectable
marker. Initially the transformation efficiency of two Agrobacterium
strains (LBA4404 and AGL1) were compared using the potato cultivars ‘Iwa’
and ‘Ilam Hardy’. Both strains resulted in similar numbers of regenerated
shoots, but there was a higher proportion of off-types among plants transformed
using the AGL1 strain. Subsequently, the cultivars ‘Karaka’, ‘Pacific’, ‘Red
Rascal’, ‘Rua’, ‘Russet Burbank’, and ‘White Delight’ were transformed with
strain LBA4404. Putatively transformed lines with kanamycin resistance were
assayed using multiplex polymerase chain reaction (PCR) with an endogenous
potato actin as an internal control. From a total of 116 lines, 105 were
confirmed as being PCR-positive for the nptII gene, of which 93 were
also PCR-positive for the presence of the cry1Ac9 gene. The amount
of Cry protein in all transgenic lines tested was less than 60 ng/g fresh
leaf tissue. The growth of potato tuber moth (Phthorimaea operculella)
larvae was inhibited by foliage from greenhouse-grown plants of 77 of the
transgenic lines (P < 0.05). Fifty-five of these resistant transgenic
lines were described as having a phenotypic appearance comparable to the
corresponding parental cultivars, when grown in the greenhouse. Southern
analysis on four highly resistant lines revealed they contained two to five
copies of the cry1Ac9 gene. Several transgenic lines severely reduced
larval growth while exhibiting a phenotype similar to their parent cultivar.
These lines warrant further investigation in the field.
Keywords Agrobacterium-mediated transformation;
genetic engineering; potato; insect resistance; Bacillus thuringiensis;
cry1Ac9; Phthorimaea operculella; potato tuber moth
H03081; Online publication date 17 March 2004; Received 10 September 2003;
accepted 5 December 2003
New Zealand Journal of Crop and Horticultural Science, 2004, Vol. 32:
39-50
0014-0671/04/3201-0039 © The Royal Society of New Zealand 2004
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