Targeted Mutagenesis of the Female-Suppressor <i>SyGI</i> Gene in Tetraploid Kiwifruit by CRISPR/CAS9
2020
Gloria De Mori | Giusi Zaina | Barbara Franco-Orozco | Raffaele Testolin | Emanuele De Paoli | Guido Cipriani
Kiwifruit belong to the genus <i>Actinidia</i> with 54 species apparently all functionally dioecious. The sex-determinants of the type XX/XY, with male heterogametic, operate independently of the ploidy level. Recently, the SyGI protein has been described as the suppressor of female development. In the present study, we exploited the CRISPR/Cas9 technology by targeting two different sites in the <i>SyGI</i> gene in order to induce a stable gene knock-out in two tetraploid male accessions of <i>Actinidia chinensis</i> var. <i>chinensis.</i> The two genotypes showed a regenerative efficiency of 58% and 73%, respectively. Despite not yet being able to verify the phenotypic effects on the flower structure, due to the long time required by tissue-cultured kiwifruit plants to flower, we obtained two regenerated lines showing near fixation of a unique modification in their genome, resulting in both cases in the onset of a premature stop codon, which induces the putative gene knock-out. Evaluation of gRNA1 <i>locus</i> for both regenerated plantlets resulted in co-amplification of a minor variant differing from the target region for a single nucleotide. A genomic duplication of the region in proximity of the Y genomic region could be postulated.
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