Dissecting the Variations of Ripening Progression and Flavonoid Metabolism in Grape Berries Grown under Double Cropping System

A double cropping system has been commercially adopted in subtropical regions in southern China, where there is abundant sunshine and heat resources. In this viticulture system, the first growing season normally starts as a summer cropping cycle; then, the vine is pruned and forced by hydrogen cyanamide, resulting in a second crop in January of the next year. Due to climate differences between the two growing seasons, flavonoid content and composition varies greatly. In this study, changes in the transcriptome of flavonoid-associated pathways were compared in berries grown under the double cropping system; in addition, the accumulation of flavonoid compounds was compared. Specific alterations in MYB transcription factors occurred in winter cropping berries around veraison. Then, the winter cropping cycle distinctly induced the flavonoid metabolic pathways while triggering the ripening-associated pathways. Notably, the climate conditions in winter cropping positively affected flavonoid biosynthesis, while the summer season took a major toll on anthocyanin accumulation. In addition, the three classes of flavonoid compounds responded differently to the changing climate; the anthocyanins and flavonols were promoted several fold, whereas no consistent increase was found for flavan-3-ols. Conclusively, flavonoid biosynthesis in grapes grown under a double cropping system showed seasonal or climatic-specific accumulation patterns. Overall design: Total RNA obtained from deseed grape berries of of Cabernet Sauvignon and Riesling at three developmental stages (E-L 35, 36 and 38) in winter cropping compared to summer control crops.

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Chen WK, Bai XJ, Cao MM, Cheng G, Cao XJ, Guo RR, Wang Y, He L, Yang XH, He F, Duan CQ, Wang J