Optimization of Agrobacterium Mediated Genetic Transformation in Paspalum scrobiculatum L. (Kodo Millet)

Abstract

An efficient and reproducible protocol for Agrobacterium tumefaciens mediated genetic transformation was developed for kodo millet (Paspalum scrobiculatum L.) by optimizing various parameters. Agrobacterium strains EHA 105 and LBA 4404 harboring plasmids pCNL 56 and pCAMBIA 2300, respectively, provided the highest transformation efficiency. Addition of acetosyringone (AS) in infection medium (200 µM-EHA 105, 250 µM-LBA 4404) and co-cultivation medium (50 µM) increased the transformation efficiency. Transient and stable expression of gus gene was confirmed with histochemical assay of infected embryos and leaves of transformed plants, respectively. The best GUS response was obtained by pretreatment of callus with an antinecrotic mixture (10 mg/L Cys + 5 mg/L Ag + 2.5 mg/L As) at infection time of 20 min followed by co-cultivation for 3 days (EHA 105) and 5 days (LBA 4404) in dark. Regenerated transgenic plants were obtained after 8 to 10 weeks of selection on callus induction medium (NAA 0.5 mg/L, BAP 1 mg/L) containing 50 mg/L Kan + 250 mg/L Cef and were rooted for 2 weeks on MS medium containing PAA (1 mg/L) and phytagel. The plantlets established in greenhouse showed normal growth. Therefore, the protocol developed in the present study can be used for development of improved varieties of kodo millet.