HighlightGrapevine red blotch interferes with the hormonal and transcriptional regulation of berry development, leading to suppression of secondary metabolism and induction of photosynthesis at late ripening stages.

No abstract

Hybrid (Vitis vinifera ×Vitis labrusca) table grape cultivars grown in the subtropics often fail to accumulate sufficient anthocyanins to achieve good uniform berry color. Growers of V. vinifera table grapes in temperate regions generally use ethephon and, more recently, (S)-cis-abscisic acid (S-ABA) to overcome this problem. The objective of this study was to determine if S-ABA applications at different timings and concentrations have an effect on anthocyanin regulatory and biosynthetic genes, pigment accumulation, and berry color of the Selection 21 cultivar, a new V. vinifera ×V. labrusca hybrid seedless grape that presents lack of red color when grown in subtropical areas. Applications of S-ABA 400 mg/L resulted in a higher accumulation of total anthocyanins and of the individual anthocyaninsanthocyanins: delphinidin-3-glucoside, cyanidin-3-glucoside, peonidin-3-glucoside, and malvidin-3-glucoside in the berry skin and improved the color attributes of the berries. Treatment with two applications at 7 days after véraison (DAV) and 21 DAV of S-ABA 400 mg/L resulted in a higher accumulation of total anthocyanins in the skin of berries and increased the gene expression of CHI, F3H, DFR, and UFGT and of the VvMYBA1 and VvMYBA2 transcription factors in the seedless grape cultivar.

-The objective of this work was to evaluate the effect of ethephon and of abscisic acid (ABA) application timing on the color of 'Rubi' Table grape. Eight treatments were evaluated: control, without application; ethephon 500 mg L -1 applied seven days after veraison (7 DAV); and two concentrations of ABA (200 and 400 mg L -1 ) arranged with three application timings at 7 DAV, at 15 days before harvest (DBH), and at 7 DAV + 15 DBH. ABA does not modify physical-chemical characteristics of the cluster and improves the color of grapes, especially when applied twice (7 DAV + 15 DBH) at the concentration of 400 mg L -1 .Index terms: Vitis vinifera, ABA, anthocyanins, plant growth regulator. Uso do etefon e épocas de aplicação do ácido abscísico para melhorar a cor da uva de mesa 'Rubi'Resumo -O objetivo deste trabalho foi avaliar o efeito do etefon e de épocas de aplicação do ácido abscísico (ABA) na cor da uva de mesa 'Rubi'. Oito tratamentos foram avaliados: controle, sem aplicação; etefon 500 mg L -1 , aplicado sete dias após o início da maturação (7 DAIM); e duas concentrações de ABA (200 e 400 mg L -1 ) arranjadas em três épocas de aplicação, aos 7 DAIM, aos 15 dias antes da colheita (DAC) e aos 7 DAIM + 15 DAC. O ABA não altera as características físico-químicas dos cachos e melhora a cor das uvas, especialmente quando aplicado duas vezes (7 DAIM + 15 DAC), à concentração de 400 mg L -1 .