ABSTRACT
Alternative selectable marker genes and selection protocols were previously reviewed by Lakshmanan et al. (2005), Altpeter and Oraby (2010) and Birch (2014). The neomycin phosphotransferase (nptII, Bower and Birch 1992) is the most frequently used selectable marker gene followed by phosphinothricin acetyltransferase (bar/pat, Gallo-Meagher and Irvine 1996; Manickavasagam et al. 2004), phosphomannose isomerase (manA, Jain et al. 2007), acetolactate synthase (als, Van der Vyver et al. 2013; Dermawan et al. 2016) and hygromycin phosphotransferase (hpt, Arencibia et al. 1998) for sugarcane transformation. Including a selective agent during the entire regeneration process but reducing the concentration of the selective agent (e.g. geneticin) during this phase reduces the occurrence of chimerism while improving transformation rates of recalcitrant genotypes (Bower et al. 1996; Basnayake et al. 2011).
