FAD2 desaturation : looking behind natural and induced variation
Résumé
The desaturase FAD2 is the main target for breeding high oleic crops. Plant breeding is based on the recombination of a diversity of alleles to select the optimal combinations for a defined trait. Classical breeding relies on the availability of alleles in natural accessions, but also in the different subgenomes in the case of polyploid crop species like camelina. Screening of selected accessions of camelina identified lines with variable oleic and linoleic acid content. Recombinant lines with specific transgression on these traits were selected in field trials and genome wide sequencing was carried out to identify potential cis or trans-regulation of FAD2 gene. However none of these recombinant lines could compare with camelina mutants obtained by CRISPR-mediated gene editing (1). These lines were for the first time evaluated in the field at Rothamsted research demonstrating the need for agronomical evaluation of edited plants (2). Interestingly, the highest oleic line showed important morphological changes that were environmentally controlled demonstrating the importance of FA desaturation in plant development. Identification of camelina lines with fine tuned ratio of polyunsaturated/monounsaturated content allows precise evaluation of the roles of these fatty acids in the response to abiotic stress. 1. C. Morineau et al., Selective gene dosage by CRISPR-Cas9 genome editing in hexaploid Camelina sativa.