Ripening is the critical step for the development of flavour quality in fruit. This character has significantly declined in many fleshy fruits over recent decades, primarily due to the focus of current breeding programs on agronomic traits such as production, firmness, and postharvest shelf life. This strategy has caused a tunnelling effect on genetic variability in many crops. This is particularly significant in strawberry, where current cultivars are derived from a narrow germplasm stock. Moreover, strawberry fruits possess two notable features: i) the fleshy part of the strawberry fruit is the result of the enlargement of the flower receptacle, while the true fruits are the dry structures called achenes, anchored on the surface of the receptacle; ii) while the hormone ethylene is essential for the ripening of climacteric fruits such as tomato, ethylene only plays a marginal role in strawberry fruits, and as such is considered non-climacteric. Therefore, improving fruit flavour in present strawberry varieties requires two important breakthroughs: 1) a precise understanding of non-climacteric and receptacle ripening regulation that will allow the targeting of relevant quality genes, and 2) the identification of unexploited allelic variants from wild germplasm to be introgressed through the generation of novel breeding lines. In our project, we are interested in generating information and tools that will help to achieve these goals. Specifically, we have followed three specific aims in this project:
1) To characterize molecularly the strawberry fruit ripening performing transcriptomics and metabolomics analyses
2) To identify and investigate the role played by key transcription factors (TFs) regulating fruit ripening
3) To uncover the gene regulatory network for these key TFs, and to study their impact on fruit quality characters
4) To identify novel genes controlling fruit quality characters of the ripe fruit using a germplasm collection of woodland strawberry (Fragaria vesca) accessions.
Overall, TRANSFR-Q project final aim is to gain deep knowledge in the molecular processes controlling strawberry fruit ripening, and identifying genes with a key role in the acquisition of quality characters in order to transfer this knowledge into new and improved breeding lines. Moreover, we plan to establish comprehensive genomic resources not only for strawberry but also for the Rosaceae community, an aspect of utmost importance since this family contains many economically important fruit trees, including apple, peach, cherry, apricot and almond.
