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High-efficiency, microprojectile-mediated cotransformation of sugarcane, using visible or selectable markers

Transient expression of the maize anthocyanin regulatory elements, R and C1, was used to optimise parameters for microprojectile-mediated delivery of DNA into sugarcane embryogenic callus. Osmotic treatment of target tissues and particle acceleration in a high-pressure helium pulse increased the fre...

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Bibliographic Details
Published in:Molecular breeding 1996, Vol.2 (3), p.239-249
Main Authors: Bower, R, Elliott, A.R, Potier, B.A.M, Birch, R.G
Format: Article
Language:English
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Summary:Transient expression of the maize anthocyanin regulatory elements, R and C1, was used to optimise parameters for microprojectile-mediated delivery of DNA into sugarcane embryogenic callus. Osmotic treatment of target tissues and particle acceleration in a high-pressure helium pulse increased the frequency of transient expression to 5-8 X 10(3) cells per bombardment, with minimal tissue damage. An average of 0.34% of transiently expressing cells developed into stably transformed, anthocyanin-pigmented proembryoids which subsequently regenerated into plantlets. However, constitutive expression of R and C1 proved deleterious, and no anthocyanin-pigmented plant survived beyond 3 cm in height. We also compared selective subculture of callus portions showing luciferase activity with antibiotic selection on medium containing G418 or phosphinothricin, upon bombardment of callus with constructs driving strong expression of luc, aphA or bar genes. Selective subculture based on luciferase activity enabled recovery of 1.4 +/- 0.5 independent transgenic plants per bombardment, compared to 19.8 +/- 3.7 independent transgenic plants per bombardment from an optimised G418 selection regimen, and no transformed plants from phosphinothricin selection. When luc and aphA on separate plasmids were coprecipitated onto microprojectiles before bombardment, 67-79% of callus lines selected for G418 resistance also showed luciferase activity detectable under a low-light camera. Southern analysis confirmed a very high cotransformation frequency, with variable copy numbers of introduced genes. The high efficiencies of gene transfer, selection and cotransformation in the optimised system, coupled with the simple initiation and regeneration of embryogenic callus, provide an effective tool for practical genetic transformation of sugarcane.
ISSN:1380-3743
1572-9788
DOI:10.1007/bf00564201