Selection and characterization of a new switchgrass (Panicum virgatum L.) line with high somatic embryogenic capacity for genetic transformation

Switchgrass (Panicum virgatum L.) is used horticulturally as an ornamental and agronomically as an animal feedstock and a putative bio-energy crop. Genetic transformation, using somatic embryogenic (SE) callus derived from mature seeds, is one strategy for improving switchgrass traits. A superior switchgrass line, HR8, was developed in this study using recurrent tissue culture selection from cv. Alamo. Eighty two percent of HR8 seeds germinated after harvest comparing to 26.8% for unselected ‘Alamo’. HR8 seeds that germinated produced 84.9% SE callus. HR8 seeds had higher endogenous abscisic acid (ABA) contents and responded differently to exogenous additions of ABA in culture. Endophytes were isolated from switchgrass seeds and callus. HR8 callus had less endophytic contamination than that of ‘Alamo’ callus. HR8 SE calli were genetically transformable using Agrobacterium. Therefore, HR8 is a superior line for generating SE callus and Agrobacterium-mediated transformation.

► An elite switchgrass line, HR8, was created through recurrent tissue culture selection.
► HR8 had exceptionally high somatic embryogenic callus production and lower seed dormancy.
► HR8 seeds had higher ABA content and responded differently to exogenous ABA.
► HR8 callus had less endophytic contamination.
► HR8 somatic embryogenic callus were transformable with Agrobacterium tumefaciens.