Production of herbicide-resistant cowpea (Vigna unguiculata L.) transformed with the bar gene

Abstract

Plant genetic engineering has opened new avenues to modify crops and has provided a powerful tool for crop improvement. The present study reports the development of regeneration and genetic transformation protocol for the Turkish cowpea cultivar Akkiz. The immature cotyledons were cultured on Murashige and Skoog (MS) medium containing 0.25-0.75 mg L-1 6-benzylaminopurine with or without 0.25 mg L-1 a-naphthalene acetic acid. Shoot regeneration varied 44.4%-83.3% with 2.1-5.0 shoots per explant. Regenerated shoots were rooted in MS medium containing 0.50 mg L-1 indole-3-butyric acid and acclimatized in the greenhouse, where they flowered and set seeds. Immature cotyledons were transformed with Agrobacterium tumefaciens strain LBA4404 harboring the recombinant binary vector pRGG containing an herbicide tolerance gene (bar) along with a uida (GUS) gene under 35S promoter. Phosphinothricin was used as a selectable marker at a concentration of 2.5 mg L-1. Putative transformants were screened by the histochemical GUS assay. Furthermore, molecular analysis revealed the presence of the introduced gene in the genome of cowpea cultivar Akkiz. The selected transgenic plants showed a resistance to Basta® nonselective herbicide at up to 10 mL L-1 of water. Putative transgenic plants retained their pigmentation and continued to grow in the greenhouse.