At ICRISAT, we have developed efficient tissue culture and transformation systems for groundnut with high transformation frequency using cotyledon explants forming adventitious shoot buds in different groundnut genotypes and leaflet explants from 2-day in vitro germinated seedlings. The transformation protocol based on cotyledon explants has been optimized for the development of transgenic groundnut capable of producing fertile plants by Agrobacterium tumefaciens -mediated gene transfer that is potentially applicable to a wide range of groundnut genotypes. The protocol uses cotyledon explants from presoaked mature seeds that can produce multiple adventitious buds that are highly amenable to A. tumefaciens infection and result in a large number of transgenic events from a given experiment. In this system, over 85% of the explants produce putative transgenic plants of which large percentage (>55%) show stable gene integration. The status of groundnut transgenics being developed by ICRISAT is listed in the following table.
Constraint
Genes
Status
Viruses
Indian peanut clump virus (IPCV)
Coat protein/ Replicase
T4-T7 plants field-tested in 2002, 2003, 2004, 2005.
5 of 50 promising events selected for resistance
Groundnut rosette-assistor virus (GRAV)
Coat Protein
35-T3 events ready for testing in Africa .
Peanut bud necrosis virus (PBNV)
Coat Protein
( N-gene )
24 of 48 T2 plants evaluated in contained field tests (2005).
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