Day length and media effects on Arachis pintoi regeneration in vitro

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.