Table 2. Wheat transformation by particle bombardment.

Reference	Target tissue	Promoter/reporter	Selectable marker	Comment
Wang et al. 1988	Cell suspension	Adh1/gus	-	Transient expression
Oard et al. 1990	Leaf base Apical tissue	Adh1/gus 35S/ gus	-	Transient expression (air gun apparatus)
Chibbar et al. 1991	Immature embryo	35S/cat 35S/gus	-	Transient expression
Daniell et al. 1991	Leaves, Immature embryo or Anther derived calli	35S/ gus Double psbA/gus	nptII -	Transient expression of the gus gene. First report of foreign gene expression in a monocot chloroplast
Shimada et al. 1991	Pollen embryos	35S/gus	-	Transient expression
Vasil et al. 1991	Cell suspension	E35S/gus	nptII, EPSPS	Generation of stable transformed callus lines expressing the marker genes
Vasil et al. 1992	Embryogenic callus (5-7 month old)	Adh1/gus	bar	Stable transformation, production of basta resistant fertile transgenic plants.
Perl et al. 1992	Scutellar calli	Act1/gus	-	Enhanced transient expression was observed when silver thiosulphate and Ca(NO3)2 was used in place of CaCl2
Vasil et al. 1993	Immature embryo, embryogenic calli (1-2 month old)	Adh1/gus Ubi/gus 35S/ gus	bar	Stable transformation. Generation of flowering transgenic plant in 7-9 months
Weeks et al. 1993	Callus derived from immature embryo	Ubi/gus	bar	Stable transformation producing nine independent lines of fertile transgenic wheat
Becker et al. 1994	Scutellar tissue of immature embryos	Act1/gus	bar	Stable transformation and Mendelian segregation of the transgene
Iglesias et al.1994	Embryonic meristem	Act1/gus 35S/gus	-	Transient expression in meristem cells, which is 10 fold less than the surrounding tissues(microtargetting).
Takumi et al. 1994	Cell lines	35S/gus 35S-35S/gus Adh /gus Act1/gus	-	Highest level of transient expression was observed by rice Act1 promoter among all the promoter/intron combinations tested
Loeb and Reynolds,1994	Microspore-derived embryoids	Ubi/gus	bar	Transient expression, detection of GUS expression in haploid plants 5 weeks post-bombardment.
Nehra et al. 1994	Isolated scutella, Scutellum callus	35S/gus Act1/gus	bar, nptII	Stable transformation and mendelian inheritance of the transgenes.
Zhou et al. 1995	Immature embryo	35S (duplicated) Ubi1	CP4, GOX	Stable transformation of wheat. The successful use of glyphosate tolerant CP4 and GOX genes as selectable markers.
Altpeter et al. 1996a	Immature embryo	Ubi1/gus	bar	Accelerated production of transgenic wheat (8-9 weeks time for generation of transgenic plants)
Altpeter et al. 1996b	Immature embryo	Ubi1/gus	bar	Integration and expression of high molecular weight (HMW) glutenin subunit 1Ax1 in wheat
Blechl and Anderson, 1996	Immature embryo	Dy10	bar	Transformation of wheat with a modified HMW glutenin subunit gene under native regulatory elements
Ortiz et al.1996	Immature embryo calli	35S/gus	hpt, bar,	Hygromycin resistance as an efficient selctable marker for wheat stable transformation
Takumi and Shimada, 1996	Immature scutellum tissue	35S/gus Act1/gus	bar	Successful cotransformation of the gus and bar genes . The authors reported the influence of culture duration on the transformation efficiency of the scutellum tissue
De Block et al. 1997	Embryogenic calli	35S	bar	Engineering of nuclear male sterility in wheat by introduction of the barnase gene under the control of tapetum-specific promoter
Lonsdale et al. 1998	Scutellar calli	Ubi1/luciferase	bar	Stable transformation of wheat by employing luciferase as a reporter gene to identify the transition from transient to stable expression
Barro et al. 1998	Scutellar tissue	Ubi/gus Act1/gus 35S	bar nptII	Low copy number and simple integration patterns in transgenic lines. This report investigated on the influence of auxins on the transformation of wheat
Leckband and Lorz, 1998	Immature embryos	Vst1/gus 35S	pat	Transformation of a stilbene synthase gene of Vitis vinifera (Vst1) for increased fungal resistance
Witrzens et al. 1998	Cultured immature embryo	Act1/gus	Ubi/ bar nptII	Generation of stably transformed plants with bar and nptII as the selectable marker. No transgenic plant was obtained with the hpt gene
Altpeter et al. 1999	Immature embryos	Ubi	bar	Transformation of a barley trypsin inhibitor gene into wheat for increased resistance to insects
Bliffeld et al. 1999	Isolated scutella	Act1 Ubi1	bar	Transformation of a barley seed chitinase gene into wheat for incresed resistance to powdery mildew disease.
Chawla et al. 1999a; Chawla et al. 1999b	Scutellum	35S/ (Bperu and C1) Act1	bar	Use of anthocyanin regulatory genes as a reporter for stable transformation of wheat
Chen et al. 1999	Immature embryos	Ubi 35S	hpt	Transformation of a rice thaumatin like protein into wheat for enhanced resistance to scab caused by Fusarium.
Harvey et al. 1999	Scutellar calli	Ubi1/luciferase	bar	Use of tissue culture regenerated plants as a source of explants resulted in a significant increase in the transformation efficiency
Ingram et al. 1999	Microspore- derived embryo	Ubi/gus	bar	Transient expression
Srivastava et al. 1999	Immature embryos	Act1 Ubi1	bar	Generation of single copy transgenic wheat based on the use of a strategy based on site-specific recombination of Cre-lox system
Stoger et al. 1999	Immature embryos	Rss1 Ubi1	bar	Expression of the insecticidal lectin from Galanthus nivalis in transgenic wheat plants for increased insect resistance
Takumi et al. 1999	Immature embryo	35S Act1 Ubi	bar	Development of transposon tagging system in wheat by transformation of maize activator (Ac) element and transformation of dissociation (Ds) element in transgenic lines expressing Ac.
Uze et al. 1999	Cultured immature embryo	Ubi/gus	Ubi/bar	Highest transformation efficiencies was obtained with linearized single stranded and double stranded plasmids
Bieri et al. 2000	Scutellum derived calli	Act1	bar	Introduction of a barley seed ribosome-inactivating protein for enhanced fungal resistance
Jordan, 2000	Immature embryos	Act1/gfp 35S	nptII	Green fluorescent protein as a visual marker for wheat transformation
Sivamani et al. 2000	Immature embryos	Ubi	bar	Transformation of a barley gene (HVA1) encoding a late embryogenesis abundant protein into wheat for tolerance to drought stress
Zhang et al. 2000	Immature embryos	Ubi	bar	Stable transformation and expression of bar and the bacterial ribonuclease gene.

Abbreviations: Act1: rice actin promoter Adh1: alcohol dehydrogenase 1 promoter bar and pat: encodes a phosphinothricin acetyl transferase Bperu and C1: regulatory elements of anthocyanin biosynthesis cat: chloramphenicol acetyl transferase Dy10: an high molecular weight glutenin subunit (HMW-GS) gene sequence containing the promoter and start site gus: encodes b -glucuronidase gfp: green fluorescent protein hpt: encodes hygromycin phosphotransferase nptII: encodes neomycin phosphotransferase psbA: promoter fragment from pea chloroplast genome 35S: Cauliflower Mosaic Virus (CaMV) 35S promoter E35S: enhanced 35S promoter Ubi1: maize ubiquitin promoter Rss1: Rice sucrose synthase 1 promoter Vst1: promoter of Vitis stilbene synthase gen