Advanced molecular tools for breeding in Mediterranean fruit trees: Genome editing approach of Ficus carica L.

Fruit-tree breeding is a lengthy process with many limitations. Classical breeding strategies using conventional cross-breeding and induced mutations have played an important role in the development of new cultivars in fruit trees. Precise genome editing could be a very useful supplementary tool for the improvement of crop plants. Various genome editing techniques including ZFNs, TALENs, and most recently CRISPR/Cas9 based approaches have been successfully employed for various crop plants including fruit trees. Previously, we used a ZFN-based approach to efficiently induce precise genome editing at specific genomic loci in fig. Furthermore, CRISPR/Cas9-based approaches hold great potential in genome editing due to their simplicity and were efficiently used in the last few years in several fruit trees. Efficient regeneration and transformation systems, a prerequisite for genome editing, were developed in several Ficus carica cultivars. Here we describe efficient CRISPR/Cas9 genome editing in fig. Transgenic fig lines carrying a mutated GUS construct (mGUS), were developed. mGUS editing, using the CRISPR/Cas9 system was confirmed by GUS staining and PCR. Figs are very attractive due to their nutritive and antioxidant properties. Yet, ripened fresh figs are highly perishable and require delicate postharvest handling. Characterizing the transcriptome of ripening fig fruits we found several genes that display altered expression during ripening and related to the ABA and ethylene hormonal processes. Currently we are using the CRISPR/Cas9 methodology to generate non-GM fig fruits that exhibit delayed ripening. The different application of CRISPR/Cas9 methodologies in fruit trees will be discussed.