1006 Plant Cell Rep (2012) 31:999–1007 Fig. 7 G418 germination assay. a T1 susceptible seedlings under 30 mg/L G418 selection after 1 week and b T1 resistant seedlings under 30 mg/L G418 selection after 1 week (Chiu et al. 1996). Hence, visual examination may be used to optimize helium pressure, shooting distance and other parameters very rapidly, and non-destructively by counting the GFP foci. The same tissues may then be used for regeneration of stable transformants, which is not possible with other maker genes requiring destructive or toxic enzyme assays. Visual marker genes like gfp can even be used for sorghum transformation without using antibiotics or herbicides as the selection agents (Gao et al. 2005a). Transgenic sorghum plants have been successfully obtained from IEs with the aid of three selective markers (Kumar et al. 2011; Grootboom et al. 2010; Gurel et al. 2009). The herbicide-resistance bar gene was used in the ﬁrst transgenic sorghum report (Casas et al. 1993). The phosphomannose isomerase (pmi) gene, which converts mannose-6-phosphate to fructose-6-phosphate (Joersbo et al. 1998), was proven to be an efﬁcient selective marker for sorghum Agrobacterium-mediated transformation (Gurel et al. 2009), and the hygromycin phosphotransferase (hpt) gene, which gives the plant resistance to the antibiotic hygromycin, was reported to be a good selective marker for sorghum transformation (Kumar et al. 2011; Carvalho et al. 2004). The neomycin phosphotransferase (nptII) gene has been shown to be successful in sugarcane microprojectile transformation (Bower and Birch 1992). It was also shown to be an efﬁcient selective marker for sorghum micropro- jectile transformation during the present study. Genetic modiﬁcation technologies play an important role in modern agriculture. An efﬁcient genetic transfor- mation system greatly enhances the ability of scientists to study gene function and improve economically important traits in crop plants. A high frequency of reliable sorghum transformation makes genetic engineering technology more practical and feasible, which will be critical in an era where the demand for food and biomaterials is ever expanding, and the amount of arable land is limited. 123 Acknowledgments We wish to thank the ARC (Australian Research Council) and Paciﬁc Seeds for their ﬁnancial support on Linkage project LP0883808. We also are grateful to the Bureau of Sugar Experimental Stations (BSES) Limited for providing the plasmids utilized in this study. Our thanks also extend to Dr. Bradley Campbell and Dr. Yue Sun for their efforts during the editing process. Open Access This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which per- mits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited. References Able JA, Rathus C, Gray S, Nguyen TV, Godwin ID (1998) Transformation of sorghum using the Particle Inﬂow Gun (PIG). Int Sorghum Millets Newsl 39:98–100 Able JA, Rathus C, Godwin ID (2001) The investigation of optimal bombardment parameters for transient and stable transgene expression in sorghum. In Vitro Cell Dev Biol Plant 37(3): 341–348 Belton PS, Taylor JRN (2004) Sorghum and millets: protein sources for Africa. Trends Food Sci Technol 15(2):94–98 Bower R, Birch RG (1992) Transgenic sugarcane plants via microprojectile bombardment. Plant J 2(3):409–416 Carvalho CHS, Zehr UB, Gunaratna N, Anderson J, Kononowicz HH, Hodges TK, Axtell JD (2004) Agrobacterium-mediated trans- formation of sorghum: factors that affect transformation efﬁ- ciency. Genet Mol Biol 27(2):259–269 Casas AM, Kononowicz AK, Zehr UB, Tomes DT, Axtell JD, Butler LG, Bressan RA, Hasegawa PM (1993) Transgenic sorghum plants via microprojectile bombardment. Proc Natl Acad Sci USA 90(23):11212–11216 Chiu WL, Niwa Y, Zeng W, Hirano T, Kobayashi H, Sheen J (1996) Engineered GFP as a vital reporter in plants. Curr Biol 6(3): 325–330 Dugdale B, Beetham PR, Becker DK, Harding RM, Dale JL (1998) Promoter activity associated with the intergenic regions of banana bunchy top virus DNA-1 to -6 in transgenic tobacco and banana cells. J Gen Virol 79:2301–2311 Elkonin LA, Pakhomova NV (2000) Inﬂuence of nitrogen and phosphorus on induction embryogenic callus of sorghum. Plant Cell Tissue Organ Cult 61(2):115–123