Changes in Anthocyanin Production during Domestication of Citrus

Abstract

Mandarin (Citrus reticulata), citron (Citrus medica), and pummelo (Citrus maxima) are important species of the genus Citrus and parents of the interspecific hybrids that constitute the most familiar commercial varieties of Citrus: sweet orange, sour orange, clementine, lemon, lime, and grapefruit. Citron produces anthocyanins in its young leaves and flowers, as do species in genera closely related to Citrus, but mandarins do not, and pummelo varieties that produce anthocyanins have not been reported. We investigated 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. A white mutant of lemon lacks functional alleles of Ruby, demonstrating that Ruby plays an essential role in anthocyanin production in Citrus. 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 and 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, confirms the derivation of commercial varieties during domestication, elucidates the relationships within the subgenus Papeda, and allows a new genetic classification of mandarins.

Retrotransposon promoter of Ruby1 controls both light‐ and cold‐induced accumulation of anthocyanins in blood orange

“…In this study, two sets of primers corresponding to CsRuby1 or internal to the Gag‐Pol region were used for qRT‐PCR analyses to detect its responsiveness to cold treatment. The expression patterns of Gag‐Pol and CsRuby1 were consistent with the changes in anthocyanin accumulation in response to cold storage in blood orange fruit peel and pulp (Figure b,c), which was similar to the observation of Butelli et al (). The results indicated that the LTR carries the elements for the low temperature induction of Gag‐Pol and CsRuby1 .…”

“…The expression patterns of Gag-Pol and CsRuby1 were consistent with the changes in anthocyanin accumulation in response to cold storage in blood orange fruit peel and pulp (Figure 3b,c), which was similar to the observation of Butelli et al (2017). The results indicated that the LTR carries the elements for the low temperature induction of Gag-Pol and CsRuby1.…”

“…Besides purple pummelo and blood orange, lemon can also synthesize anthocyanins in young fruit under ample light (Figure a). The active Ruby1 promoter of lemon was named as R L , which contains a 5,435‐bp retrotransposon named Tcl3 (Butelli et al, ) and is located at −1,005 bp relative to the ATG start codon (Figure b). The R L ‐Del (1,506 bp upstream of ATG, including 5′ LTR of Tcl3) was fused to a GUS gene (Figure c), and the construct was transformed into Arabidopsis .…”

“…The active Ruby1 promoter of lemon was named as R L , which contains a 5,435-bp retrotransposon named Tcl3 (Butelli et al, 2017) and is located at −1,005 bp relative to the ATG start codon (Figure 6b).…”

Chitosan–catechin coating as an antifungal and preservable agent for postharvest satsuma oranges

“…Technology that delays maturation and/or manages fruit ripening to maintain fruit quality and storability will increase the market and economic value of the fruit and provide consumers with a high‐quality product (Lorenzo, Batlle, & Gómez, ; Shenasi, Aag, & Aidoo, ). Citrus is the first choice of consumers among all fruit crops (Butelli et al, ). Moreover, citrus fruits and juices are the main human sources of vitamin C, which is an essential component of human nutrition (Lee, ; Dugrandjudek et al, ; Xu et al, ).…”