Efficient and Reproducible DNA Delivery Methods for Trees Genome Editing

Genome editing aimed at manipulating and improving targeted genes is widely used for the study of basic biological processes and specific improvement of desirable and novel characters in commercially important tropical as well as subtropical fruit, nuts and forest trees. The technique involves precise and accurate changing and editing of the genome through DNA insertion, deletion, or replacement via multiple genome editing tools. Trees are considered an invaluable commodity that not only provides energy, fiber and materials but also safeguards global climate and such genome editing techniques are reliable and have great potential to further improve these imperative traits and allow us to boost productivity, enhance wood quality and improve resistance to several biotic and abiotic stresses. Tree breeding is considered a lengthy procedure that often requires a few to more than 10 years due to the tree’s long juvenile phases, large size and asexual propagation nature. Traditional tree breeding strategies via conventional cross-breeding and induced mutations have led to the development of new fruit tree cultivars. However, precise tree genome editing techniques might play a valuable supplementary tool for their improvement. Over the last decade, numerous methods have been exploited for DNA delivery, such as the application of biotechnology in breeding via Agrobacterium-mediated transformation has been proven successful and possesses a huge potential with increased availability of sequenced genomes of Fruits and nuts that can be efficiently used for the improvement of the trait. Various other potential genome editing tools such as ZFNs, TALENs and most recently CRISPR/Cas9 have been effectively utilized for several fruit trees. Various improvements and alterations have been introduced worldwide to enhance the efficiency and reproducibility of the existing delivery protocols. In this review, various DNA delivery methods for genome editing together with their fundamental principles, procedures, efficacy and future prospects will be discussed.