Ms. Brar et al., Genotypic response of cowpea Vigna unguiculata (L.) to in vitro regeneration from cotyledon explants, IN VITRO-PL, 35(1), 1999, pp. 8-12
A plant regeneration system applicable to 17 cowpea genotypes was developed
. Cotyledons were initiated on 1/3 MS medium containing 15 to 35 mg N-6-ben
zyladenine (BA) per l (66.6 to 155.3 mu M) for 5 to 15 d. For shoot regener
ation, the explants were transferred to a medium containing 1 mg BA per l (
4.4 mu M ). Within 1 wk, shoot formation was visible at the proximal end of
the cotyledons. Regeneration percentages (1% to 11%) and the numbers of sh
oots (4 to 12 per explant) were significantly influenced by genotype. Cultu
re duration and BA concentration in the initiation stage significantly affe
cted regeneration capacity. Explants initiated on media containing 15 mg BA
per l for 5 d resulted in the highest percentage of explants capable of re
generation. Conversely, the highest number of shoots was obtained from expl
ants initiated on media supplemented with 35 mg BA per l. Whole plants were
obtained on a plant growth regulator-free medium. To our knowledge, this i
s the first report of plant regeneration from U.S. commercial cowpea cultiv
ars and breeding lines. This system is adaptable to diverse cowpea genotype
s and will facilitate cowpea genetic transformation.