|XU, WENPING - Shanghai Jiaotong University|
|PENG, HUI - Nanjing Agricultural University|
|LIU, XIANJIN - Jiangsu Academy Agricultural Sciences|
|HUANG, LUHONG - Hunan Academy Of Agricultural Sciences|
Submitted to: Plant Physiology and Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/25/2014
Publication Date: 7/4/2014
Citation: Xu, W., Peng, H., Yang, T., Liu, X., Huang, L. 2014. Effect of calcium on strawberry fruit flavonid gene expression and anthocyanins accumulation. Plant Physiology and Biochemistry. 82:289-298.
Interpretive Summary: Anthocyanins are the red to blue pigments present in many fruits and vegetables that appeal visually to consumers. Anthocyanins are also recognized as compounds with potential health-benefits, such as anti-inflammatory and anti-carcinogenic activity, cardiovascular disease prevention, obesity control, and alleviation of diabetes. Strawberry is an economically important crop, and its fruit are rich in anthocyanins and related bioactive compounds. To determine which genes are most important for anthocyanin accumulation in strawberries, the expression patterns of anthocyanin synthesis pathway genes were compared in two genotypes that bear either red or yellow fruit, and those genes highly expressed in only red fruit were identified. It was further found that calcium spray treatment of strawberry plants boosted expression of the same set of anthocyanin pathway genes and increased anthocyanin accumulation in fruit. These results provide new knowledge that can be used by plant breeders or growers to enhance the color and health-benefits of strawberries.
Technical Abstract: Strawberry fruit contain phenolic compounds such as anthocyanins, which have beneficial effects against oxidative stress mediated diseases. Two diploid strawberry (Fragaria vesca) inbred lines, Ruegen F7-4 (red fruit) and YW5AF7 (yellow fruit) were used to study the regulation of anthocyanin biosynthesis in fruit. Ruegen F7-4 had similar total phenolic and anthocyanin contents to commercial octoploid cultivar (F. x ananassa) cv. Seascape, while YW5AF7 exhibited low total phenolic content, and had no antocyanin accumulation. Foliar spray of CaCl2 boosted total phenolic content, especially anthocyanins, by more than 20% in Seascape and Ruegen F7-4. Expression patterns of flavonoid pathway genes showed that in green stage fruit, the expression levels of almost all of flavonoid pathway genes were comparable in Ruegen F7-4 and YW5AF7. However, at the turning and ripe stages key genes involved in anthocyanin synthesis, such as flavanon 3-hydroxylase, dehydroflavonol 4-reductase, anthocyanidin synthase and UDP-glucosyltransferase, were much more highly expressed in Ruegen F7-4 than in YW5AF7 fruit. Foliar calcium treatment stimulated expression of the same set of key biosynthetic genes. Most flavonoid pathway genes are single copy. For the genes with more than one copy, those responsible for anthocyanin synthesis were identified. Taken together, these results suggest that lack of anthocyanin synthesis in YW5AF7 is caused by suppression of flavonoid pathway genes by an upstream regulator(s). Moreover, this upstream regulator(s) can be modulated by calcium signaling.