Anthocyanin accumulation in the red‐fleshed grape germplasm ZhongShan‐HongYu through bulked segregant analysis and RNA‐seq

The role of UV radiation in the accumulation of anthocyanin in 'Gros Colman' (Vitis vinifera L.), a light-sensitive cultivar, was examined by using berry sections prepared from the softened green berries at veraison. The sections were exposed to diffuse sunlight under covering materials such as glass plate, polyolefin film (PO), poly vinyl chloride film (PVC), UV-proof PVC, ethylenetetrafluoroethylene (ETFE), polycarbonate resin plate (PC), fiber-reinforced acrylic resin plate (FRA) for 72 hr. The accumulation of anthocyanin in the berry skins under diffuse sunlight was greatly reduced with the covering materials which prevent the penetration of UV light. Artificial irradiation with an UV lamp (peak wavelength: 352 nm) greatly promoted the accumulation of anthocyanin. With increasing light intensity in the UV-A region (320-400 nm) up to 0.4 W·m-2, the anthocyanin content markedly increased, reached a plateau and then levelled off at 2.3 W·m-2. Increasing the intensity of white light up to 8.5 W·m-2 induced a gradual accumulation of anthocyanin. When UV irradiation was combined with white light at about 4.1 W·m-2, the accumulation of anthocyanin was further enhanced. These results suggest that UV light is involved in the accumulation of anthocyanin in 'Gros Colman' grapes. Hence, UV permeability of covering materials in the protected culture should be considered.

Southeast Anatolia is located in close proximity to the center of origin of grapes and is an important grape producing area of Turkey. The important location of this region for grape genetic diversity together with its diverse ecological conditions may have led to the development of grape germplasm that is unique to this region. However, so far little has been done to genetically analyze this grape germplasm. In this study, we genetically analyzed 55 grape cultivars originating from six different provinces of this region using 14 simple sequence repeat (SSR) loci and a number of ampeolographic characteristics. Based on these analyses, one case of synonymous and four cases of homonymous grape cultivars were identified. The contribution of our results to better characterization of the grape germplasm of the region as well as future germplasm management and breeding efforts is discussed.

Supplying monochromatic blue LED light during the day, but not at night, promotes early coloration and improves anthocyanin accumulation in the skin of grape berries. Specific light spectra, such as blue light, are known to promote the biosynthesis and accumulation of anthocyanins in fruit skins. However, research is scarce on whether supplement of blue light during different periods of one day can differ in their effect. Here, we compared the consequences of supplying blue light during the day and night on the accumulation of anthocyanins in pigmented grapevine (Vitis vinifera) berries. Two treatments of supplemented monochromatic blue light were tested, with light emitting diodes (LED) disposed close to the fruit zone, irradiating between 8:00 and 18:00 (Dayblue) or between 20:00 and 6:00 (Nightblue). Under the Dayblue treatment, berry coloration was accelerated and total anthocyanins in berry skins increased faster than the control (CK) and also when compared to the Nightblue condition. In fact, total anthocyanin content was similar between CK and Nightblue. qRT-PCR analysis indicated that Dayblue slightly improved the relative expression of the anthocyanin-structural gene UFGT and its regulator MYBA1. Instead, the expression of the light-reception and -signaling related genes CRY, HY5, HYH, and COP1 rapidly increased under Dayblue. This study provides insights into the effect of supplementing monochromatic LED blue light during the different periods of one day, on anthocyanins accumulation in the berry skin.

Girdling and grapevine leafroll associated viruses affect berry weight, colour development and accumulation of anthocyanins in ‘Crimson Seedless’ grapes during maturation and ripening

In our study, we discovered a fragment duplication autoregulation mechanism in 'ZS-HY', which may be the reason for the phenotype of red foliage and red flesh in grapes. In grapes, MYBA1 and MYBA2 are the main genetic factors responsible for skin coloration which are located at the color loci on chromosome 2, but the exact genes responsible for color have not been identified in the flesh. We used a new teinturier grape germplasm 'ZhongShan-HongYu' (ZS-HY) which accumulate anthocyanin both in skin and flesh as experimental materials. All tissues of 'ZS-HY' contained cyanidin 3-O-(6″-p-coumaroyl glucoside), and pelargonidins were detected in skin, flesh, and tendril. Through gene expression analysis at different stage of flesh, significant differences in the expression levels of VvMYBA1 were found. Gene amplification analysis showed that the VvMYBA1 promoter is composed of two alleles, VvMYBA1a and 'VvMYBA1c-like'. An insertion of a 408bp repetitive fragment was detected in the allele 'VvMYBA1c-like'. In this process, we found the 408bp repetitive fragment was co-segregated with red flesh and foliage phenotype. Our results revealed that the 408bp fragment replication insertion in promoter of 'VvMYBA1c-like' was the target of its protein, and the number of repeat fragments was related to the increase of trans-activation of VvMYBA1 protein. The activation of promoter by VvMYBA1 was enhanced by the addition of VvMYC1. In addition, VvMYBA1 interacted with VvMYC1 to promote the expression of VvGT1 and VvGST4 genes in 'ZS-HY'. The discovery of this mutation event provides new insights into the regulation of VvMYBA1 on anthocyanin accumulation in red-fleshed grape, which is of great significance for molecular breeding of red-fleshed table grapes.

Transcriptional analysis of the early ripening of ‘Summer Black’ grape in response to abscisic acid treatment

Root restriction affects anthocyanin accumulation and composition in berry skin of ‘Kyoho’ grape (Vitis vinifera L. × Vitis labrusca L.) during ripening

The grape (Vitis vinifera) is one of the earliest domesticated fruit crops and, since antiquity, it has been widely cultivated and prized for its fruit. The aim of this investigation was to characterize grape germplasm that have been under cultivation in Iran for a long time. Sixteen fruit parameters were studied in 23 grape cultivars. A high variability was found in the evaluated grape cultivars, and significant differences were found between them in all fruit attributes. Fruit yield, cluster size, berry size, total soluble solids (TSS), and titratable acidity (TA) showed a wide variation. Most cultivars had a relatively medium berry size; three had a berry weight higher than 3.50 g. Very diverse berry skin color were observed, white to black, while the dominant color of berry was yellowish green. There were high positive correlations between cluster and berry traits (weight and dimensions) and also negative correlation between TSS and TA. Cluster and principal component analyses showed a considerable fruit diversity in the studied grape germplasm. Parameters with high discriminating values were those related to berry size. The wide range in fruit trait characteristics of Iranian grapes might be considered as characterizing the large gene pool that contributed to the domestication process of grape. Also, clonal selection and conservation of the highly diverse autochthonous grapes are recommended.

Anthocyanin accumulation and biosynthesis are modulated by regulated deficit irrigation in Cabernet Sauvignon (Vitis Vinifera L.) grapes and wines

Grapevine is the world's commercial horticulture crop. Poor coloration of grapes is one of the problems in grape production. Climate changes could negatively affect grape quality by reducing color formation. The effect of high temperatures on anthocyanin content and composition in the main red-producing grapes would help estimate their phenotypic change and perhaps predict whether they will be able to sustain the attributes of high-quality grapes in the context of climate change. Climate changes played an important role in lack sufficient berry color especially high temperature inhibited L-phenylalanineammonialyase (PAL). L-phenylalanineammonialyase improved accumulation of anthocyanin in the skin of grape berries. Environmental factors like light, temperature and irrigation are effective in either grapes coloration or discoloration. Plant growth regulators like Brassinosteroids (BRs), Jasmonic acid (JA), Salicylic acid (SA) and Abscisic acid (ABA) are accelerating the accumulation of anthocyanin in grapes berry skin. So it is very important to know how grapes coloration, the effect of plant growth regulators and environmental factors on grapes coloration.

The Anatolian region of modern-day Turkey is believed to have played an important role in the history of grapevine (Vitis vinifera L.) domestication and spread. Despite this, the rich grape germplasm of this region is virtually uncharacterized genetically. In this study, the amplified fragment length polymorphisms (AFLP)-based genetic relations of the grapevine accessions belonging to the 2 economically important Anatolian table grape varietal groups known as V. vinifera 'Misket' (Muscat) and V. vinifera 'Parmak' were studied. Thirteen AFLP primer combinations used in the analyses revealed a total of 1495 (35.5% polymorphic) and 1567 (34.6% polymorphic) DNA fragments for the 'Misket' and 'Parmak' varietal groups, respectively. The unweighted pair-group method with arthimetic averaging (UPGMA) cluster analysis and principal coordinate analysis (PCA) conducted on polymorphic AFLP markers showed that both varietal groups contain a number of synonymous (similar genotypes known by different names) as well as homony mous (genetically different genotypes known by the same name) accessions. Our results also showed that 6 of the Anatolian 'Misket' genotypes were genetically very similar to V. vinifera 'Muscat of Alexandria', implying that these genotypes might have played some role in the formation of this universally known grape cultivar. Finally, the close genetic similarities found here between 'Muscat of Alexandria' and V. vinifera 'Muscat of Hamburg' support the recent suggestion that 'Muscat of Hamburg' probably originated from 'Muscat of Alexandria' through spontaneous hybridizations. Overall, the results of this study have implications for not only preservation and use of the Anatolian grape germplasm, but also better understanding of the historical role that this region has played during the domestication of grapes.

The influence of sunlight exclusion from grape clusters at different phenological stages on berry composition, especially anthocyanin accumulation in berry skin, was investigated. Sunlight was excluded from clusters at three different stages: fruit set to about 1 week preveraison, about 1 week preveraison to about 1 week postveraison, and about 1 week postveraison to maturity for the red grape cv. Jingxiu (Vitis vinifera L.) over two seasons and three cultivation conditions (in the field in 2011 and in the greenhouse and rain shelter in 2012). Sunlight exclusion at the different stages did not consistently affect berry weight, soluble solids content, or titratable acidity at maturity. However, sunlight exclusion from fruit set to 1 week preveraison consistently significantly increased anthocyanin content both at 1 week postveraison and at maturity, compared to the clusters exposed to sunlight throughout fruit development (control). Clusters with sunlight excluded from 1 week preveraison to 1 week postveraison accumulated less anthocyanins than control clusters at 1 week postveraison, while re-exposure to sunlight resulted in recovery of anthocyanin synthesis to a similar total content to control clusters at maturity. The absence of sunlight from 1 week postveraison to maturity did not significantly affect anthocyanin content compared to the control. The increase of anthocyanin content by sunlight exclusion from fruit set to 1 week preveraison might have a practical application for production of more anthocyanins in red grape berry skin.

Sweet cherry, an economically important horticultural crop, has strong antioxidant activity. The fruits contain compounds potentially beneficial to human health—particularly anthocyanins, which are synthesized in cytosol and predominantly accumulated in vacuoles. Although anthocyanin levels differ among dark-red, blush, and yellow sweet cherry cultivars, the regulatory mechanism of anthocyanin transport and accumulation is not well understood in this species. In this study, we identified 53 glutathione S-transferase genes (PavGSTs) from sweet cherry and found that PavGST1 expression was well correlated with anthocyanin accumulation in cultivars with different fruit skin colors. TRV-mediated virus-induced silencing of PavGST1 decreased anthocyanin accumulation in sweet cherry fruits and downregulated the expressions of anthocyanin biosynthetic and regulatory genes. In addition, transient overexpression of PavGST1 promoted anthocyanin accumulation. Furthermore, yeast one-hybrid and dual-luciferase assays revealed that PavMYB10.1 and PavMYB75 directly bind to different MYB binding sites of the PavGST1 promoter (MBS-1 and MBS-3) to activate PavGST1 transcription. According to our results, PavGST1 plays a central role in sweet cherry fruit anthocyanin accumulation. Our findings provide novel insights into the coordinative regulatory mechanisms of PavGST1 and PavMYBs in anthocyanin accumulation in sweet cherry.

The formation of color in plants is significantly dependent on anthocyaninpigments. Grape species vary in color due to the differences in anthocyanin accumulation. It is widely recognized that both biotic and abiotic conditions may have an impact on anthocyanin synthesis in plants. The underlying molecular mechanisms by which external application of hyperoside impacts anthocyanin formation in grapes, however, have received little attention. In the current study,the transcriptome of Gemstone seedless grape was examined using high-throughput RNA sequencing at various developmental stages reply to both control and hyperoside treatments. The results of this study suggested that the major genes controlling anthocyanin accumulation in response to the externalinjection of hyperoside could be VvMYB62, VvPAL, VvCHS, and VvF3'5'H.Quantitative reverse transcription PCR (RT-qPCR) results were used to confirm the changes in the expression levels of the genes encoding the anthocyanin biosynthesis pathway under the control and hyperoside treatments. Using a transient transformation system, it was discovered that VvMYB62 was shown to regulate the anthocyanin accumulation at both the transcriptional and posttranslational levels and could be influenced by the external administration of hyperoside. In grape embryogenic calli, hyperoside could specifically suppress theexpression of VvMYB62 and anthocyanin accumulation. In this instance, the VvMYB62 characterisation brought attention to the significance of exogenous hyperoside-induced anthocyanin accumulation. Therefore, the results demonstrated that VvMYB62 could be hindered in the process of grape during anthocyanin accumulation caused by hyperoside. These findings offer excellent candidate genes in the future breeding of novel grape varieties in addition to serving as a crucial reference for understanding the underlying molecular processes of hyperoside suppression of anthocyanin formation in plants.

The anthocyanin composition and concentration of various organs of teinturier grape Yan-73 were studied throughout the growing season. Nineteen anthocyanins were identified by HPLC-MS as monoglucosides and their derivatives. Anthocyanin composition and concentration varied among grape organs and by developmental stage. Skin anthocyanins were mainly composed of malvidin derivatives, while peonidin derivatives were the most dominant anthocyanins in the pulp. Both malvidin and peonidin derivatives were predominant components in carpopodia (swollen pedicel at point of berry attachment), berry pedicels, leaf lamina, vein and petioles, and living bark at the base of the shoot. Anthocyanins were very low before veraison, and then increased sharply at veraison in berry skin and pulp. Anthocyanins in carpopodia and berry pedicels also increased sharply, although occurring later than in berry skin and pulp. Anthocyanins were high in young and senescing leaf lamina and low in expanding and mature lamina. Anthocyanins did not vary much in leaf vein and petiole tissue, or in bark, throughout the growing season.