Stable expression of gus (β-glucuronidase) gene following Agrobacterium-mediated transformation of peanut (Arachis hypogaea L.)

In vitro regeneration protocol compatible to Agrobacterium-mediated genetic transformation was developed for peanut (Arachis hypogaea L.) variety DM-1 using young leaflet explants. Transformation experiments were conducted using Agrobacterium tumefaciens LBA4404 harbouring binary plasmid pBI121, containing GUS (beta-glucuronidase) reporter gene and nptII (neomycin phosphotransferase II) gene conferring resistance to kanamycin. Regeneration of multiple shoots was achieved via organogenesis from infected leaflet explants on MS medium supplemented with 5.0 mg/l BAP + 0.5 mg/l Kn. Selection of the transformed shoots was carried out by applying kanamycin since kanamycin resistant gene was used for the transformation experiments. The selection pressure of kanamycin was gradually increased up to 300 mg/l in obtaining transformed shoots. The selected kanamycin resistant shoots were rooted on half the strength of MS medium containing 0.2 mg/l NAA and 50 mg/l kanamycin. Transformed rooted plantlets were successfully transferred to soil where four of the plants produced viable seeds. The stable expression of the GUS gene was observed among the various tissues of leaf, stem, flower and root of transformed plantlets. The seed developed from the transformed plant also showed GUS activity detected through histochemical staining.