Nuclear and plastid genetic engineering of plants: Comparison of opportunities and challenges

Transplastomic plants for innovations in agriculture. A review

“…Plastids have become attractive targets for genetic engineering efforts as compared with nuclear transgenic technologies (reviewed in Meyers et al 2010) due to several potential advantages. These include (1) absence of gene silencing, epigenetic, and/or position effects, which eliminates the high variation in gene expression and thus in protein accumulation levels among independent transgenic lines; (2) high protein expression levels due to very high plastid DNA copy number per chloroplasts/cells/organ resulting in the accumulation of large amounts of the transgene's product in the chloroplast/ cell/organ; (3) possibility of multigene engineering (including cDNAs instead of full genes) through the use of transgene stacking in operons in a single transformation event; and (4) almost complete absence of pleiotropic effects due to subcellular compartmentalization of the transgene products (e.g., Staub et al 2000;Bock 2001Bock , 2013De Cosa et al 2001;Daniell et al 2002;Quesada-Vargas et al 2005;Verma and Daniell 2007;Oey et al 2009;Ruhlman et al 2010;Meyers et al 2010).…”

“…These include (1) absence of gene silencing, epigenetic, and/or position effects, which eliminates the high variation in gene expression and thus in protein accumulation levels among independent transgenic lines; (2) high protein expression levels due to very high plastid DNA copy number per chloroplasts/cells/organ resulting in the accumulation of large amounts of the transgene's product in the chloroplast/ cell/organ; (3) possibility of multigene engineering (including cDNAs instead of full genes) through the use of transgene stacking in operons in a single transformation event; and (4) almost complete absence of pleiotropic effects due to subcellular compartmentalization of the transgene products (e.g., Staub et al 2000;Bock 2001Bock , 2013De Cosa et al 2001;Daniell et al 2002;Quesada-Vargas et al 2005;Verma and Daniell 2007;Oey et al 2009;Ruhlman et al 2010;Meyers et al 2010). From the biosafety point of view, the plastid technology (5) significantly increases transgene containment because plastids are maternally inherited in most crops, and therefore, the transgenes are not transmitted by pollen (Section 5) and outcrossing with weeds and other plants is not possible (Daniell et al 1998Daniell 2002;Hagemann 2004Hagemann , 2010.…”

“…There are fundamental differences between the nuclear and chloroplast genomes, e.g., proteins are not known to be exported from plastids, so the two methods are not always interchangeably applicable. Since plastid transformation has its own advantages as discussed above, the pros and cons of nuclear versus plastid genetic engineering have to be carefully examined for various biotechnology applications (reviewed in Daniell et al 2002;Meyers et al 2010).…”

“…Alterations of the plastid genome represent a promising possibility for high-level, clean, and safe expression of proteins (and other products) in cost-effective commercial applications. The advantages and challenges of plant molecular pharming are extensively reviewed elsewhere Daniell 2006;Bock 2007Bock , 2014Verma and Daniell 2007;Chebolu and Daniell 2009;Rybicki 2009;Bock and Warzecha 2010;Cardi et al 2010;Meyers et al 2010;Wani et al 2010;Lössl and Waheed 2011;Maliga and Bock 2011;Obembe et al 2011;Scotti et al 2012;Ahmad and Mukhtar 2013). Although several plastid-derived vaccine antigenes have already been tested in animal models (Lössl and Waheed 2011), to our knowledge no transplastomic plants have been licensed for biopharmaceutical use (Section 4).…”

Advances in genetic engineering of marine algae

“…(Opabode, 2006). This method is also technically challenging because of the large size and low copy number of Ti plasmids, which leads to difficulties in plasmid isolation and manipulation (Meyers et al, 2010). Several developed and advanced binary vector systems are attempting to mitigate these problems and help integrate multiple foreign genes into the same T-DNA Gelvin, 2008, Tzfira et al, 2005).…”