Allelic differences in the key genes of betalain biosynthesis in table beet accessions with contrasting root color from the VIR collection

Abstract

Background. Table beet (Beta vulgaris L.) contains a great amount of naturally red-colored betanins. A number of enterprises are forced to import foreign dyes because the reserves of domestic plant raw materials are insufficient. With this in view, the development of cultivars with high betalain pigment content is now required.Materials and methods. Allelic differences were screened in the key genes of the betalain biosynthesis pathway among table beet accessions with various root color from the VIR collection using the Sanger DNA sequencing method.Results and discussion. For the first time we identified a nonsense mutation in the CYP76AD1 gene in cv. ‘Serdolik’ with yellow flesh; it led to the truncation of the functional P450 domain. We suggested that the detected polymorphism correlated with phenotypic switching because the well-known role of CYP76AD1 was essential for the red betalain accumulation. Moreover, a number of missense mutations in cv. ‘Avalanche’ in the first exon of the BvDODA1 gene were found. These mutations were probably associated with the expression of the uncolored phenotype. An in silico analysis revealed highly homologous copies of CYP76AD5, located tandemly on chromosome 9. Attention should be paid to these copies, together with the CYP76AD6 gene, as they seem the most preferable targets for a knockout to increase the red pigment content.Conclusion. It is possible to identify the best table beet accessions for further genome editing among a previously selected high-betanin group. In addition, this study revealed the allelic differences in the key genes of the betalain biosynthesis pathway. These results will be useful for the development of DNA molecular markers to facilitate the selection of table beet forms with required properties.