Agriculture Reference
In-Depth Information
cotyledon-based ef
cient regeneration system for the production of large
numbers of independently transformed peanut plants (Sharma and
Anjaiah 2000). Shoot formation is rapid and proli
c, and a large pro-
portion of these shoots developed into fertile plants, which provide new
options for peanut breeding through transgenics. The work on develop-
ing a transgenic peanut (cv. JL 24) rich in
-carotene begun at ICRISAT, is
using
Agrobacterium
-mediated genetic transformation with the maize
phytoene synthase gene (
psyI
) driven by an
At oleosin
promoter (for
seed-speci
β
c expression in oil bodies). The polymerase chain reaction
(PCR) analysis with gene-speci
c primers and Southern hybridization
with gene-speci
c probes revealed effective introduction of transgene(s)
into many primary events (T
0
). Currently, the material is in the T
2
generation and the biochemical analysis from these events show a
multifold (up to 5.4
gg
1
) increase in
-carotene compared with the
untransformed control. Further work is in progress to identify the most
promising lines for eventual integration into a breeding program for
developing
μ
β
-carotene-rich peanut cultivars (ICRISAT 2011). Further-
more, the newly identi
β
ed advanced breeding lines (CS 39, ICGV 05155,
and ICGV 06040) rich in grain Fe and Zn were transformed with maize
psy1
and tomato
-LYC
genes to produce marker-free (Puchta 2003)
putative transgenic events. The genomic revolution has provided
researchers many opportunities to stack multigenes or proteins simulta-
neously to generate plants with more ambitious phenotypes (Naqvi et al.
2009a,b). It appears that peanut genetic engineers will be able to generate
transgenic events carrying genes for nutritional traits and resistance to
abiotic and biotic stresses to develop peanuts that resist stress and
produce peanuts with enhanced nutritional traits.
β
B. Aflatoxin
A
atoxin is a serious quality problem in peanut (see Section I). More-
over, agricultural products contaminated with mycotoxins drastically
limit the access of producers to the global markets, which have set high
standards for food safety. Progress in peanut breeding for a
atoxin
resistance has been limited due to the low level of resistance to different
components of resistance (preharvest seed infection and a
atoxin pro-
duction,
in vitro
seed colonization by
A.
avus
) in the germplasm, their
variable performance due to high GEI, lack of reliable screening proto-
cols, and limited understanding of the genetic factors controlling differ-
ent components of resistance to a
atoxin contamination (Nigam et al.
2009). Advances in genetic transformation in peanut have led to the
development of a few transgenic events containing antifungal genes. For
