Positive selection: a plant selection principle based on xylose isomerase, an enzyme used in the food industry

Genetic Transformation of a High Molecular Weight Glutenin (Glu-1Dx5) to Rice cv. Fatmawati

“…During the regeneration experiment, shoots were abundantly obtained, but green plantlets were obviously rare, especially on calluses that were bombarded with pK+Dx5B and pBar25 (growing on bialaphos-containing medium). Transformation efficiency may be suboptimal in the presence of toxic substrates like bialaphos or hyrgomycin, because dying untransformed cells may inhibit transformed cells from proliferating by secreting inhibitors or preventing transport of essential nutrients to the living transformed cells (Haldrup et al, 1998). After two to three subcultures on bialaphos-containing NB 5 medium, 11 putative transgenic rice plants were regenerated, but only 9 plants were able to grow further (Fig.…”

Olive

“…The vector, which includes ipt and maize transposable element Ac for removing the ipt gene, seems to be promising (Ebinuma et al, 1997). Other approaches might involve xyla (xylose isomerase) (Haldrup et al, 1998) and pmi (phosphomannose isomerase) genes, both of which confer the capacity to use nonmetabolizable substrates. Finally, for highly regenerative cultures, it may be possible to eliminate the marker gene and select on the basis of physiological or morphological parameters, e.g., the response to toxins, culture filtrate, salt/drought resistance, etc.…”

Recent Advances in Fruit Species Transformation

“…Previously, results obtained with this approach demonstrated higher yields than when the toxic selective agents were employed, and seems to be broadly applicable to crop plants (Miki & McHugh, 2004). Some of the most widely used are the AtTPS1/glucose (Leyman et al, 2006); galT/galactose (Joersbo et al, 2003); xylose isomerase (Haldrup et al, 1998);D-aminoacid/dao1 (Alonso et al, 1998) and the pmi/mannose (Joersbo et al, 1998). Probably, one of the most used one in fruit species is the gene pmi that encodes the enzyme phosphomannose isomerase (EC 5.3.1.8) that catalyzes the reversible interconversion of mannose 6-phosphate and fructose 6-phosphate.…”