Application of new breeding techniques in fruit trees

Climate change and rapid adaption of invasive pathogens pose a constant pressure on fruit industry to develop improved varieties. Aiming to accelerate the development of better adapted cultivars, new breeding techniques have emerged as a promising alternative to meet the demand of a growing global population. Accelerated breeding, cisgenesis and CRISPR/Cas genome editing hold significant potential for crop trait improvement, which have proven to be useful in several plant species. This review focuses on the successful application of these technologies in fruit trees to confer pathogen resistance, tolerance to abiotic stress, and to improve quality traits. In addition, we review the optimization and diversification of CRISPR/Cas genome editing tools applied to fruit trees, such as multiplexing, CRISPR/Cas-mediated base editing and site-specific recombination systems. Advances in protoplast regeneration and delivery techniques, including the use of nanoparticles and viral-derived replicons, are described for the obtention of exogenous DNA-free fruit tree species. Regulatory landscape and broader social acceptability for cisgenesis and CRISPR/Cas genome editing are also discussed. Altogether, this review provides an overview of the versatility of applications for fruit crop improvement, as well as current challenges that deserve attention for further optimization and potential implementation of new breeding techniques.