Agriculture Reference
In-Depth Information
are seed storage proteins that make up a considerable amount of the total
seed protein, and it is impossible to determine which ones or how many
of them can be eliminated without sacri
cing quality or viability. One
study clearly demonstrated that silencing of
Ara h 2
and
Ara h 6
in the
peanut genome yielded viable seeds and there was no signi
cant differ-
ence in fungal contamination of seeds between the transgenic and
nontransgenic controls (Chu et al. 2008). Two approaches were used
to identify naturally occurring mutations in allergen genes or alterations
in the allergenic proteins of peanut. Primarily, targeting-induced local
lesions in genomes (TILLING), a reverse-genetics approach, was devel-
oped to screen populations for individuals carrying mutations in speci
c
genes. The TILLING approach was used to identify mutations affecting
the allergens and other seed traits (including fatty acid desaturases
involved in the high oleic trait) in peanut (Knoll et al. 2011). The two
most signi
ed to date consist of a dis-
rupted start codon in
Ara h 2.02
and a premature stop codon in
Ara h
1.02
. Homozygous individuals were recovered in succeeding genera-
tions for each of these mutations. The former was found to lack the Ara h
2.02 protein. In the latter, several Ara h 1 protein isoforms were elim-
inated or signi
cant allergen mutations identi
cantly reduced as well (Ozias-Akins et al. 2009; Knoll
et al. 2011).
The second approach is to screen for the levels of protein
allergens with antibodies produced against the major peanut allergens
or use serum from the blood of peanut allergic individuals to screen
for the differences in allergenic reactivity of the individual allergens in
different peanut cultivars (Koppelman et al. 2001; Schmitt et al.
2004; Hurlburt et al. 2011). The old
peanut cultivar was
previously gamma-irradiated to produce mutations in speci
'
NC 4
'
ctraits
in order to improve nutritional quality of peanuts. This collection,
referred to as
andhousedatNorthCarolina
State University, was screened for the levels of Ara h 2 and for
the differences in IgE binding to Ara h 2 (unpublished information).
In this study, one peanut line from the collection missed one of the Ara
h 2 isoforms, some missed Ara h 3, 40 kDa isoforms (Hurlburt et al.
2011), and others had signi
“
the Gregory mutants
”
cant reduction in the levels of Ara h 1
protein (unpublished information). In a few cases, even when a reduc-
tion in the level of an allergen was not observed, the IgE binding was
signi
cantly lower, implying a difference in the amino acid sequence
and therefore the encoding gene. This
rmed in a
study that showed a single-nucleotide polymorphism (SNP) in the
Ara h 2
gene resulted in a signi
finding was con
cant loss in IgE binding (Ramos et al.
2009).
