An Agrobacterium rhizogenes strain R1000-mediated efficient hairy root transformation protocol for common bean

Common bean (Phaseolus vulgaris L.) is a globally important grain and vegetable legume crop, providing a substantial portion of the diet protein and minerals for many people in the developing world. However, the genetic studies and improvement on this crop has long been impeded by its recalcitrance to Agrobacterium-mediated whole plant genetic transformation. Established Agrobacterium rhizogenes-based hairy root transformation in common bean heavily relies on the strain K599.

In order to develop an efficient alternative protocol for hair transformation in common bean, the efficiency of Agrobacterium rhizogenes strain R1000 in inducing hairy roots from 6-day-old seedlings with root below cotyledons excised by the soaking and smearing method were tested. The binary plasmid pBI121 with the reporter gene GUS (pBI121-GUS) or eGFP (pBI121-eGFP) driven by the constitutive promoter was used for transformation and rapid identification of the transgenic hairy roots.

We established a strain R1000-based system for the induction of hairy roots in common bean. The plant receptor genotypes and infection methods were optimized, which led to a high transformation rate of hairy roots up to 60%. This method therefore provides a useful alternative means for functional genomic studies in common bean.