Abstract
Flavonone 3 hydroxylases (EC 1.14.11.9) are key enzymes in the synthesis of anthocyanins and other flavonoids. Such compounds are involved in seed coat colour and stem pigmentation. Lupinus mutabilis (tarwi) is a legume crop domesticated in the Andean region, valued for the high protein and oil content of its seeds. Tarwi accessions are being selected for cultivation in Europe under defined breeding criteria. Seed coat colour patterns are relevant breeding traits in tarwi, and these are conditioned by anthocyanin content. We identified and isolated part of the tarwi flavonone 3-hydroxylase gene (LmF3h) from two accessions with distinct seed coat colour patterns. Two partial LmF3h paralogues, with predicted 20% amino-acid changes but little predicted tertiary structure alterations, were identified in the coloured seed genotype, while only one was present in the white seed genotype. Upon selection and validation of appropriate reference genes, a RT-qPCR analysis showed that these paralogues have different levels of expression during seed development in both genotypes, although they follow the same expression patterns. DNA and transcription analyses enabled to highlight potential F3H paralogues relatable to seed coat pigmentation in tarwi and, upon biochemical and genetic confirmation, prompt marker-assisted breeding for relevant phenotypic traits associated with flavonoid synthesis.
Highlights
Flavonoids are important secondary metabolites that include chalcones, flavones, flavonols, flavandiols, anthocyanins, and proanthocyanidins or condensed tannins
Anthocyanins are deposited in the tissues via two biosynthesis pathways, which is well-described in several studies that point to the involvement of structural and regulatory genes [6]
Based on soybean and narrow-leaved lupin flavanone 3-hydroxylase (F3H) gene sequences, we amplified an orthologous region in the tarwi genome
Summary
Flavonoids are important secondary metabolites that include chalcones, flavones, flavonols, flavandiols, anthocyanins, and proanthocyanidins or condensed tannins. They are associated with positive effects, for instance as antioxidant, antibacterial, anti-cancer, anti-mutagenic, anti-atherosclerosis, and anti-inflammatory agents In plants, they play important roles in protection against biotic and abiotic stresses, act as fertility regulators, and in auxin biosynthesis. In several legume species such as Glycine max, Medicago truncatula, M. sativa and Phaseolus vulgaris, studies of characterization, expression, and function of the F3H gene have been carried out in different tissues to better understand the role of this gene [12,13,14,15], but in species of the genus Lupinus the information is still scarce. Brown seed coat is a desirable agronomic trait, several studies in various species have been performed to elucidate seed coat pigmentation mechanisms
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