Plant genetic transformation refers to the technology that exogenous gene or DNA fragment are purposefully inserted into the recipient plant genome in certain way, thus obtaining a plant with new genetic traits. The recipient cells not only retain varieties of original good traits, but also have the new traits expressed by the exogenous genes. Therefore, in addition to predominant theoretical significance, the genetic transformation of plant also has a profound application prospects in plant variety modification.
Plant genetic transformation methods commonly include microparticle bombardment, Agrobacterium-mediated transformation, electroporation, pollen tube pathway, microinjection, PEG method, virus-mediated method, etc.. But microparticle bombardment and Agrobacterium tumefaciens-mediated are so far still considered as the most widely used method with high repeatability and stability.
Targeted genome editing has been used to rapidly, easily and efficiently modify endogenous genes in a wide variety of organisms by many biological researchers.
The sequence-specific nucleases (SSNs), such as ZFNs, TALENs and the CRISPR/Cas9 system, generate DNA double-strand breaks (DSBs) at targeted sites in the genome. SSNs enable precise genome engineering by introducing DNA double-strand breaks (DSBs) that subsequently trigger DNA repair by non-homologous end joining (NHEJ) or homologous recombination (HR). By exploiting NHEJ and HR, SSNs can be used to generate targeted genome modifications including mutations, insertions, replacements and chromosome rearrangements. TALENs and CRISPR systems were crowned one of the 10 breakthroughs of the year by Science magazine in 2012 and 2013, respectively.