Arachis pintoi Krap. et Greg. is a stoloniferous wild perennial peanut whic
h is well adapted to low pH soils and shade. Tissue culture of A. pintoi ma
y be useful for genetic transformation and other genetic studies. An experi
ment with A. pintoi was performed to evaluate the effects of four day lengt
hs (0, 8, 16, and 24 h) and growth regulators on callus production and bud
formation in vitro. A Murashige and Skoog (MS) basal salts medium was used
for all stages. Tissues underwent three stages of development: (1) callus i
nduction on medium MQC (2.0 mg L-1 indole-3-acetic acid [IAA] and 1.0 mg L-
1 kinetin) or medium MSC (1.0 mg L-1 IAA and 0.5 mg L-1 6-benzylaminopurine
[BAP]); (2) bud induction on medium MQS (1.0 mg L-1 IAA and 4.0 mg L-1 EAP
) or medium 113 (2.5 mg L-1 IAA) 2 2 mg L-1 thidiazuron [TDZ], and 0.5 mg L
l BAP); and (3) shoot development on medium IBA (0.1 mg L-1-butyric acid [I
BA]), medium MSNH (MS with no growth regulators), or medium MQNH (MS with r
educed vitamin concentrations). Callus weight on medium MQC was greater tha
n on MSG, and mean callus weight over media on the 0, 16, and 24-h day leng
ths were greater than at 8 h. At the bud induction stage, calli on 8-h day
length yielded a greater number of buds than the other day lengths. At the
shoot development stage, 8 and 16-h day lengths were superior to 0 and 24 h
. A recommended protocol for A. pintoi is callus induction on medium MQC at
16-h day length followed by bud induction on medium 113 (with IBA, TDZ and
BAP) at 8 h and shoot development on a medium containing a very low level
of IBA and using a 16-h day length.