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ARS Home » Pacific West Area » Riverside, California » National Clonal Germplasm Repository for Citrus » Research » Publications at this Location » Publication #330397

Title: Changes in anthocyanin production during domestication of citrus

Submitted to: Molecular Biology and Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/4/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary: Interpretive summary Anthocyanins are water-soluble phenolic compounds responsible for the red, blue and purple colour of most angiosperm plants. Anthocyanins are produces by some but not all Citrus species. The pathway of anthocyanin biosynthesis is well characterized and all the structural genes that encode the core biosynthetic enzymes have been identified from many species. The Ruby gene, which encodes a MYB transcription factor controlling anthocyanin biosynthesis. Almost all the natural variation in pigmentation by anthocyanins in Citrus species can be explained by differences in activity of the Ruby gene, caused by point mutations, deletions and insertions of transposable elements. Comparison of the allelic constitution of Ruby in different species and cultivars also helps to clarify many of the taxonomic relationships in different species of Citrus.

Technical Abstract: Mandarin (C. reticulata), citron (C. medica) and pummelo (C. maxima) are imortant fruit species of the genus Citrus and parents of the interspecific hybrids that constitute the most familiar commercial varities of citrus: sweet orange, sour orange, clementine, lemon lme and grapefruit. Citron and its hybrids produce anthocyanins in young leaves and flowers as do species in genera closely related to Citrus, but mandarin and pummelo varities do not. We investigatre the activity of the Ruby gene, which encodes a MYB transcription factor controlling anthocyanin biosynthesis, in different accessions of a range of Citrus species and in domesticated cultivars. Almost all the natural variation in pigmentation by anthocyanins in Citrus species can be explained by differences in activity of the Ruby gene, caused by point mutations, deletions and insertions of transposable elements. A white mutant of lemon lacks functional alleles of Ruby, demonstrating that Ruby plays an essential role in anthocyanin production in Citrus. Comparison of the allelic constitution of Ruby in different species and cultivars confirms the hybrid origin of commercial varieties during domestication, elucidates the relationships within the subgenus Papeda and allows a new genetic classification of mandarins.