title: Inside out: high-efficiency plant regeneration and Agrobacterium-mediated transformation of upland and lowland switchgrass cultivars.
abstract: Selection of pre-embryogenic callus from a core structure from mature seed-derived callus is the key for high-efficiency plant regeneration and transformation of switchgrass different cultivars. Switchgrass (Panicum virgatum L.) has been identified as a dedicated biofuel crop. For its trait improvement through biotechnological approaches, we have developed a highly efficient plant regeneration and genetic transformation protocol for both lowland and upland cultivars. We identified and separated a pre-embryogenic "core" structure from the seed-derived callus, which often leads to development of highly regenerative type II calluses. From the type II callus, plant regeneration rate of lowland cultivars Alamo and Performer reaches 95%, and upland cultivars Blackwell and Dacotah, 50 and 76%, respectively. The type II callus was also amenable for Agrobacterium-mediated transformation. Transformation efficiency of 72.8% was achieved for lowland cultivar Alamo, and 8.0% for upland cultivar Dacotah. PCR, Southern blot and GUS staining assays were performed to verify the transgenic events. High regenerative callus lines could be established in 3 months, and transgenic plants could be obtained in 2 months after Agrobacterium infection. To our knowledge, this is the first report on successful plant regeneration and recovery of transgenic plants from upland switchgrass cultivars by Agrobacterium-mediated transformation. The method presented here could be helpful in breaking through the bottleneck of regeneration and transformation of lowland and upland switchgrass cultivars and probably other recalcitrant grass crops.
authors.affiliation: Department of Grassland Science, China Agricultural University, No. 2 Yuanmingyuan Xilu, Haidian District, Beijing, 100193, People's Republic of China.
authors.forename: Yan-Rong
authors.initials: YR
authors.lastname: Liu
authors.forename: Hui-Fang
authors.initials: HF
authors.lastname: Cen
authors.forename: Jian-Ping
authors.initials: JP
authors.lastname: Yan
authors.forename: Yun-Wei
authors.initials: YW
authors.lastname: Zhang
authors.forename: Wan-Jun
authors.initials: WJ
authors.lastname: Zhang
mesh_terms: D060054:Agrobacterium / Q000187:drug effects / Q000502:physiology*; D015139:Blotting, Southern; D003470:Culture Media / Q000494:pharmacology; D008897:Panicum / Q000187:drug effects / Q000196:embryology / Q000235:genetics* / Q000502:physiology*; D030821:Plants, Genetically Modified; D016133:Polymerase Chain Reaction; D012038:Regeneration / Q000187:drug effects; D014170:Transformation, Genetic / Q000187:drug effects
chemical_list: D003470:Culture Media