S01 - Session O1 - An LTR retrotransposon may activate the PsMYB10.2 gene expression and promote anthocyanin biosynthesis in the fruit flesh of Japanese plum. A success history of the CRISPR-Cas9 enrichment sequencing strategy

Authors: Maria José Aranzana *, Arnau Fiol, Federico Jurado-Ruiz, Sergio García, Christian Dujak, Elena López-Girona, Igor Pacheco

Much of the variability in agronomic traits is caused by large as well as small and middle scale structural variants (SVs), which highlights the relevance of the identification and characterization of complex variability between genomes for plant breeding. We used CRISPR-Cas9 enrichment combined with long-read sequencing technology to resolve the MYB10 region on linkage group 3 (LG3) of Japanese plum ( Prunus salicina ) in a pool of varieties. The enrichment was confirmed by aligning the long reads to the plum reference genomes and de novo assembly was constructed for each of the pooled varieties, which also allowed detection, at the haplotype level, of the variability in this region. We identified an LTR retrotransposon inserted in the promoter of the PsMYB10.2 gene that may activate gene expression in fruit flesh and initiate anthocyanin biosynthesis. The gene function was validated through transient expression in yellow-flesh Japanese plum fruits, which acquired red flesh pigmentation due to an increase of anthocyanin levels. Finally, we developed molecular markers for marker assisted selection (MAS).