Cassava tuberous roots are rich in starch but deficient in micronutrients such as provitamin A. The cassava cultivar Carvita-25 is a yellow variant of a white-fleshed cassava genotype (Adira-4) obtained through friable embryogenic callus. The following study aimed to ascertain substantial disparities in metabolite profiles and gene transcripts associated with carotenoid-related characteristics. Genotype Carvita-25 contains β-carotene and its derivative apocarotenoid, responsible for the yellow coloration of the tubers. The metabolite profile exhibited discrepancies in metabolite composition between the cultivars Adira-4 and Carvita-25. Genotype Adira-4 contains the highest levels of amino acid compounds, peptides, and their derivatives, while genotype Carvita-25 contains more amine-type compounds. Differential transcription levels were notable among the genes responsible for carotenoid biosynthesis, Manes.02G081700.1 (PSY1). An enhanced transcription level of PSY1 was evident in Carvita-25 compared with Adira-4, while the lower transcription level of PSY2 resulted in Carvita-25 compared with Adira-4. The GO (gene ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) analyses revealed the upregulation of 2,000 genes and downregulation of 1,772 genes in Carvita-25 compared with Adira-4. These comprise cytochrome P450 (CYP82D47), and bHLH family transcription factors were the candidate regulators of carotenoid-related genes in root tubers. This information can be further applicable to developing strategies for improving the quality of cassava plants rich in carotenoid compounds.
Cassava genotypes, apocarotenoids, metabolites, phytoene synthase, transcriptome, yellow-fleshed cassava
Carvita-25, a mutant cassava, has appeared to contain beta carotene and apocarotenoid metabolites with provitamin-A functions. The discrepancies in phytoene synthase genes and PSY1 and cytochrome 450 (CYP82D47) have been the identified primary factors contributing to variances in the carotenoid profile of Carvita-25 from Adira-4.