Agriculture Reference
In-Depth Information
these subsets for seed quality, quantify the environment and G
E
effects, and identify stable germplasm with improved seed character-
istics for use in breeding. The evidence suggests that global warming is
signi
×
cantly affecting nutritional quality of food crops, and peanut is no
exception. More importantly, it will be interesting to investigate how
elevated atmospheric CO
2
per se
or in interaction with drought and heat
stress will impact seed quality, including a
atoxin contamination. There
is also a need to investigate the effect of global warming on peanut seed
protein allergens. The other critical issues to investigate should include
whether exceptionally high oleate peanut germplasm is more suscepti-
ble to cold injury (at seed
filling stage) (Sun 2005) and a
atoxin con-
tamination (Xue et al. 2003, 2005).
Oil quantity and quality are important seed quality traits in peanut. It
is encouraging to know that germplasm and breeding lines exist with oil
content as high as 55
60%. SSR markers associated with high or low oil
content have been further reported. Moreover, the discovery of high
oleate (O/L ratio
-
3 often reported in cultivated
peanut) germplasm (F435-2) and its use in breeding programs led to
development and release of peanut cultivars with improved oil chemis-
try that are commercially grown in the United States. Gene-based
markers such as SNPs and high-throughput assays are available to
conduct molecular breeding for the high oleate trait in peanut using
F435-2 or its derivatives (cultivars/elite germplasm). Using these
resources and marker-aided backcrossing, researchers successfully
introgressed the high oleate trait into Tifguard, which is a cultivar
resistant to root-knot nematode. An AFLP-based SCAR marker associ-
ated with resistance to seed infection by
A.
>
40 as opposed to the 1
-
avus
may also be integrated
into the breeding program. The targeted breeding for developing grain
Fe- and Zn-dense peanut cultivars is yet to begin. Several germplasm
accessions or advanced breeding lines with high Fe and Zn grain
contents are in the public domain for use in peanut breeding. Efforts
are underway to sequence the peanut genome, which will provide
valuable resources for genome mapping, marker development, and
molecular breeding.
A cotyledon-based ef
cient regeneration system has been perfected to
produce a large number of independently transformed peanut plants
through
Agrobacterium
-mediated genetic transformation system. There
have been claims regarding the successful breeding of transgenic pea-
nuts using the maize
psyI
gene driven by the
At oleosin
promoter, which
have shown a substantial increase in
-carotene compared with the
untransformed control. Transgenic peanuts containing the antifungal
genes chitinase/glucanase accumulated signi
β
cantly less toxin than
