Anthocyanins Accumulation and Related Gene Expression in Red Orange Fruit Induced by Low Temperature Storage

Abstract

The aim of this work was to study the impact of moderately long storage periods at 4 degrees C upon red orange [Citrus sinensis (L.) Osbeck] anthocyanins production and the expression of structural genes involved in their biosynthesis such as phehylalanine ammonia lyase (PAL), chalcone synthase (CHS), dihydroflavonol 4-reductase (DFR), and UDP-glucose flavonoid glucosyl transferase (UFGT). Our results showed that low temperature-induced anthocyanins accumulation in red orange juice vesicles after 75 days reached values eight times higher than those kept at 25 degrees C. Furthermore, real-time polymerase chain reaction showed that expression of PAL, CHS, DFR, and UFGT was strongly induced during low temperature exposure since levels of all transcripts increased at least 40-fold with respect to control samples. Interestingly, in orange fruits subjected to a brief exposure at low temperature (45 days) and subsequently kept at 25 degrees C, the anthocyanins content dropped although samples still maintained higher levels of these pigments than those registered in control oranges. Concordantly, the expression of chs, dfr, and ufgt declined upon return to control conditions, but it was always much higher in samples subjected to brief cold induction than in the control samples. On the contrary, the amount of PAL transcripts became negligible immediately after the temperature change from 4 to 25 degrees C, thus indicating that "early" and "late" genes, respectively, implicated in the first and in the last steps leading to the anthocyanins, might be affected by different regulation mechanisms.

Fruit skin color and the role of anthocyanin

“…Most of the structural genes in fruit crops have been isolated and well characterized (Boss et al 1996;Piero et al 2005;Ubi et al 2006;Matus et al 2010). The structural genes (Table 3) involved in anthocyanin synthesis are coordinately expressed and their levels of expression positively related to the degree of anthocyanin concentration Piero et al 2005;Matus et al 2010;Crifó et al 2011).…”

“…The structural genes (Table 3) involved in anthocyanin synthesis are coordinately expressed and their levels of expression positively related to the degree of anthocyanin concentration Piero et al 2005;Matus et al 2010;Crifó et al 2011).…”

Light-Induced Expression of a MYB Gene Regulates Anthocyanin Biosynthesis in Red Apples

“…), Vaccinium sp. such as cranberry (Vaccinium macrocarpon) and bilberry (Vaccinium myrtillus), eggplant (Solanum melongena), and lychee (Litchi chinensis), multiple flavonoid structural genes are coregulated for anthocyanin synthesis or in many of these fruit anthocyanin synthesis is enhanced by sunlight (Tyas et al, 1998;Matsuzoe et al, 1999;Zhou and Singh, 2000;Li et al, 2001;Jaakola et al, 2002;Kim et al, 2003;Kataoka and Beppu, 2004;Steyn et al, 2004;Tsuda et al, 2004;Jia et al, 2005;Lo Piero et al, 2005;Anttonen et al, 2006;Halbwirth et al, 2006). In none of these cases has a MYB or bHLH regulator specific for induction of anthocyanin synthesis in fruit been isolated.…”

Differently expressed ‘Early’ flavonoid synthesis genes in wheat seedlings become to be co-regulated under salinity stress

“…Similarly, in red colored oranges, the transcription of Chs, Dfr and Ufgt differing from Pal (phenylalanine ammonia-lyase) is affected by brief low temperature stress (Lo Piero et al 2005). In rice, the transcription of Pal and Chs is not induced by salinity stress, although that of Dfr and Ans (anthocyanidin synthase) is (Ithal and Reddy 2004).…”

“…Intensification of the flavonoid synthesis and expression of the related genes under stress conditions was widely reported in diverse plant species (Ithal and Reddy 2004;Lo Piero et al 2005;Walia et al 2005;Ma et al 2014). The accumulation of flavonoids and expression of those genes in response to stress are reported to be genotype dependent.…”