Grape Genotypes Research Articles

An efficient strategy for developing genotype identification markers based on simple sequence repeats in grapevine

Microsatellites are valuable resources for breeding and genetic studies of crop species. The development of simple sequence repeat (SSR) markers, which are applied across closely related cultivars, has been slow, labor-intensive, and expensive, with a low success rate. In this study, we demonstrate an efficient strategy for developing cross-species, amplifiable polymorphic SSR markers from grapevine (Vitis vinifera) based on sequence comparison and in silico polymerase chain reaction amplification of the genome sequences of grape cultivars. A total of 21 primer sets targeting unique SSR loci were screened from polymorphism and heterozygosity analyses of 13 grape cultivars and four wild species. The number of alleles varied from 3 to 12, with a mean of 7.52 alleles per locus. The lowest and highest observed heterozygosity values were 0.24 and 0.82, respectively, with an average of 0.54. Polymorphic information content values for the primer sets ranged from 0.32 to 0.86, with an average of 0.70. We successfully identified genetic relationships among 17 grape genotypes using the unweighted pair group method with arithmetic average and principal coordinates analysis of the SSR markers. The results suggest that the strategy developed in this study is applicable to high-throughput cross-amplifiable SSR marker development for the identification of genotype, genetic study, and examination of genetic diversity in grapevines.

Changes in the chlorophyll content of grape leaves could provide a physiological index for responses and adaptation to UV‐C radiation

Stilbenes are a group of phytoalexins that play an important role in grapevine (Vitis) basal immunity and can be induced by biotic and abiotic stresses. The levels of chlorophylls, the main pigments in plant cells, can also indicate the tolerance of plants to various stresses. Here, the response of different grapevine genotypes to UV‐C radiation treatment was tested and the abundance of chlorophyll in the Hoe29 and Ke53 genotypes was observed to increase significantly within 6 h of UV‐C treatment. Conversely, chlorophyll levels decreased markedly in the Augster Weiss and Müller–Thurgau genotypes. Furthermore, stilbene abundance increased substantially in the Hoe29, Ke53, Ke83 and Pinot Blanc genotypes, but increased only slightly in Augster Weiss and Müller–Thurgau. The expression of resveratrol synthase, which encodes a key enzyme in the stilbene synthesis pathway, increased in Hoe29, Ke53, Ke83 and Pinot Blanc following UV‐C treatment, in a manner consistent with stilbene accumulation. In addition, we observed that reactive oxygen species (ROS) provide a key trigger in physiological responses and changes in secondary metabolite contents. In summary, the results from this study support a link between ROS, chlorophyll levels and genetic diversity for stilbene abundance in different grape genotypes, providing insights into mechanisms for plant physiological and biochemical responses and adaptations to stress.

Genetic relationships of some local and introduced grapes (Vitis vinifera L.) by microsatellite markers

In this study, the genetic relationships of 29 grape genotypes were defined with six SSR (simple sequence repeat) markers, and 65 polymorphic bands were identified, with matrix correlation (r) of 0.79. The expected heterozygosity (He) ranged from 0.783 (VrZAG62) to 0.869 (VVMD7) and the observed heterozygosity (Ho) from 0.483 (VrZAG62) to 0.897 (VVS2). According to the results, the smaller main cluster included only one ancient cultivar, ‘Buca Razakısı’. Foça Karası’, an ancient cultivar in the large main group, was separated from other grapes varieties. The first sub-cluster (S1) formed by mainly introduced cultivars included three cultivars, ‘Cabernet Sauvignon’, ‘Cabarnet Franc’ and ‘Merlot’. The second sub-cluster (S2) was the largest group, and included 19 cultivars, ‘Semillion’, ‘Alicante Boushet’, ‘Delbele’, ‘Çeşme Pembesi’, ‘Grenache’, ‘Öküzgözü’, ‘Petit Syrah’, ‘Papaz Karası’, ‘Colombard’, ‘Harsleleh’, ‘Moiseylative’, ‘Şika’, ‘Müşküle’, ‘Ohannes’, ‘Cinsaut’, ‘Kırmızı Şam’, ‘Kozak Gemresi’, ‘Siyah Gemre’ and ‘Yuvarlak Razakı’. The third sub-cluster (S3) included four cultivars, ‘Cardinal’, ‘Italia’, ‘Hafızali’ and ‘Malbee’. ‘Hafizali is an ancient cultivar and is included in this group. The fourth sub-cluster included only one ancient cultivar, ‘Pek Üzümü’. Based on the rates of similarities of the cultivars included in this study, the highest rate was recorded for ‘Öküzgözü-Petit Syrah’ (93%) in the second sub-cluster. The results reported here are important as the first steps towards better characterization of these grape genotypes and will aid future germplasm management and breeding efforts.

Genome-wide association study of berry-related traits in grape [Vitis vinifera L.] based on genotyping-by-sequencing markers

ABSTRACTDeciphering the genetic control of grape berry traits is crucial for optimizing yield, fruit quality, and consumer acceptability. In this study, an association panel of 179 grape genotypes comprising a mixture of ancient cultivars, landraces, and modern varieties collected worldwide were genotyped with genotyping-by-sequencing using a genome-wide association approach based on 32,311 single-nucleotide polymorphism (SNP) markers. Genome-wide efficient mixed-model association was selected as the optimal statistical model based on the results of known control loci of grape berry color traits. Many of the associated SNPs identified in this study were in accordance with the previous QTL analyses using biparental mapping. The grape skin color locus was found to be associated with a mybA transcription factor on chromosome 2. Two strong and distinct association signals associated with berry development periods were found on chromosome 16. Most candidate genes of the interval were highlighted as receptor-like protein kinase. For berry weight, significant association loci were identified on chromosome 18, as previously known, and on chromosome 19 and chromosome 17, as newly mapped. Berry flesh texture was newly located on chromosome 16; candidate genes in the interval were related to calcium. Berry flavor was determined on chromosome 5. Genomic regions were further investigated to reveal candidate genes. In this work, we identified interesting genetic determinants of grape berry-related traits. The identification of the markers closely associated with these berry traits may be useful for grape molecular breeding.

Effects of Colchicine Treatments on Some Grape Rootstock and Grape Varieties at Cotyledon Stage

The present study was conducted to polyploidy possibility induction of grapes in the experiment, apical meristem was treated by colchicine. The factorial experiment based on randomized completely design with tree replications. The factors including different colchicine concentrations (0 as control, 1 g L -1 , 2 g L -1 , 3 g L -1 , 4 g L -1 , 5 g L -1 , 6 g L -1 )and four diploidgrape genotypes cv. ‘Gök Üzüm’ ( Vitis vinifera L.) which came from conventional ancient time and have a perfect adaptation to the territory, and cv. ‘Trakya İlkeren’ ( Vitis vinifera L.) was bred in last two decades in Turkey, and ‘Isabella’ ( Vitis labrusca L.) and 41 grape rootstock[Chasselas ( Vitis vinifera L.) x ( Vitis berlandieri Planch.)] were used. With this purpose eight colchicine doses were dropped to meristematic part of young plantlets twice a day (at 8.30 am and 18:00 pm) during 3 days when first true leaves emerge in greenhouse (25°C during day and 20°C at night) . The morphological and cytological parameters were evaluated 16 weeks after the polyploidization treatments. Based on the size and shape, and density of stomata, the number of chloroplasts in guard cells, and chromosome counting in the root tip-end indicated that these descendants were diploids 2 n =2 x =38 like their parents that colchicine-induced mutation was failed in tested grape genotypes for tetraploid induction. On the other hand, only in the cv. ‘Trakya İlkeren’ an aneuploidy was observed by 5 g L -1 colchicine treated plantlet. Aneuploid ‘Trakya İlkeren’ plantlet was identified as 2n = 2x = 40. It is seeming that grape genotypes hardly response to colchicine induction for genome doubling. This is the first report for colchicine-inducedaneuploid in grapes.

OVIPOSITION PREFERENCE AND BIOLOGY OF FRUIT FLIES (DIPTERA: TEPHRITIDAE) ON GRAPE VINE GENOTYPES

ABSTRACT Grape orchards are highly affected by oviposition of fruit flies on grape berries, which compromises the productivity and quality of the grapes. The goal of this study was to evaluate the susceptibility of American, European, and hybrid grape genotypes to Anastrepha fraterculus and Ceratitis capitata (Diptera: Tephritidae) under laboratory conditions (25 ± 2ºC, 60 ± 10% RH, and 14-hour photophase). The assays were conducted by evaluating oviposition preference through choice and no-choice (antibiosis) tests. The choice test was set up using circular arenas (diameter: 300 mm) with 10 grapes per genotype. The no-choice test was set up using 150 grapes per genotype which were placed inside plastic boxes (417 x 297 x 289 mm). After exposure of the grapes to one or two couples of fruit flies per genotype in choice and no-choice tests, respectively, the grapes were transferred to transparent plastic containers (750 mL). The number of eggs per grape and its viability were evaluated. The no-choice test also evaluated the biological cycle of the fruit flies. The assays were conducted in a completely randomized design with 15 replicates. The most preferred grapes for oviposition by A. fraterculus were Cabernet Sauvignon, Niagara Rosada, and BRS Cora, while C. capitata mainly preferred Isabel Precoce grapes. We observed the complete development of fruit flies in the Moscato Embrapa grapes, but this only occurred with C. capitata. All genotypes evaluated were considered susceptible to A. fraterculus and C. capitata. However, the fruit flies expressed differences in preference for oviposition and host quality.

Genetic inter-relationships among Chinese wild grapes based on SRAP marker analyses

Sequence-Related Amplified Polymorphism (SRAP) markers were used to assess genetic inter-relationships among 39 grape genotypes. These included 22 indigenous Chinese grape species/varieties, the north American V. riparia and the European V. vinifera L. 'Thompson seedless' and 'Pinot noir'. Of the 72 SRAP primer combinations tested, 25 primers generated 135 reliable bands, with an average of 5.52 bands per primer pair. Further analysis shows that 106 of 135 bands were generated by 25 polymorphic primer pairs, with a polymorphism efficiency of 79 %. The similarity coefficients of SRAP polymorphism varied from 0.463 to 0.981 among the genotypes analysed. A dendrogram analysis divided the 39 Vitis accessions into 21 groups with similarity coefficients of 0.83. It reveals broadly similar genetic relationships among the genotypes examined to those previously determined using classical taxonomic methods. Our results define V. heyneana subsp. ficifolia and V. baihensis as subspecies of V. heyneana and V. bashanica, respectively. We question the placement of V. davidii var. cyanocarpa and V. davidii var. ningqiangensis as varieties in V. davidii.

Molecular Characterization and Genetic Relationships of Some Stress Tolerant Grape Rootstock Genotypes as Revealed by ISSR and SSR Markers

Grapevine rootstocks are a complex group of plants; most of them are interspecific hybrids evolved using parent genotypes having inherent tolerance to biotic and abiotic stresses. Fifteen species and interspecific hybrids of grape rootstocks along with three Vitis vinifera cultivars from IARI germplasm unit were analyzed with ten ISSR and seven SSR primers combinations. These ISSR produced 69 scorable bands with band size ranged from 200 to 1500 bp, PIC from 0.66 to 0.86 and primer heterozygosity ranged from 0.71 to 0.88. While, SSR primers detected a total of 24 alleles across 15 genotypes with PIC from 0.43 to 0.78 and primer heterozygosity from 0.49 to 0.81.The genetic similarity among the 15 grape genotypes using ISSR and SSR ranged from 0.27 to 1.00 in ISSR and 0.05 to 1.00 in SSR analysis. The genetic similarity matrices using ISSR analysis ranged from 27.0 to 85.0% and SSR 5.0 to 83.0%, respectively. The Vitis species Dogridge and Salt Creek had the highest similarity coefficient of 85% with ISSR analysis, while the interspecific hybrids 1103 Paulsen and 110 Richtier had the maximum similarity coefficient of 83% as identified by SSR analysis. The two marker systems formed two main clusters which were almost similar to that of PCA values. The principal coordinate analysis further helped in depicting the variability among species and hybrids of grape genotypes in three dimensional modes. In case of ISSRs, the first three coordinates accounted 51.92% for the existing variability, while with SSRs the variability accounted is 59.69%. The results revealed that ISSR and SSR markers could be exploited for genetic diversity analysis among the highly heterozygous grape rootstock species and interspecific hybrids.Plant Tissue Cult. & Biotech. 28(1): 77-90, 2018 (June)

Global transcriptome analysis of grapevine (Vitis vinifera L.) leaves under salt stress reveals differential response at early and late stages of stress in table grape cv. Thompson Seedless

Among the different abiotic stresses, salt stress has a significant effect on the growth and yield of grapevine (Vitis vinifera L.). In this study, we employed RNA sequence based transcriptome analysis to study salinity stress response in grape variety Thompson Seedless. Salt stress adversely affected the growth related and physiological parameters and the effect on physiological parameters was significant within 10 days of stress imposition. A total of 343 genes were differentially expressed in response to salt stress. Among the differentially expressed genes (DEGs) only 42 genes were common at early and late stages of stress. The gene enrichment analysis revealed that GO terms related to transcription factors were over-represented. Among the DEGs, 52 were transcription factors belonging to WRKY, EREB, MYB, NAC and bHLH families. Salt stress significantly affected several pathways like metabolic pathways, biosynthesis of secondary metabolites, membrane transport development related pathways etc. 343 DEGs were distributed on all the 19 chromosomes, however clustered regions of DEGs were present on chromosomes 2, 5, 6 and 12 suggesting probable QTLs for imparting tolerance to salt and other abiotic stresses. Real-time PCR of selected genes in control and treated samples of grafted and own root vines demonstrated that rootstock influenced expression of salt stress responsive genes. Microsatellite regions were identified in ten selected salt responsive genes and highly polymorphic markers were identified using fifteen grape genotypes. This information will be useful for the identification of key genes involved in salt stress tolerance in grape. The identified DEGs could also be useful for genome wide analysis for the identification of polymorphic markers for their subsequent use in molecular breeding for developing salt tolerant grape genotypes.

The occurrence of phosphoenolpyruvate carboxykinase (PEPCK) in the pericarp of different grapevine genotypes and in grape leaves and developing seeds

ABSTRACTThe occurrence of phosphoenolpyruvate carboxykinase (PEPCK) and pyruvate orthophosphate dikinase (PPDK) was determined in the ripe pericarps of several grape genotypes. Moreover, the abundance pattern of PEPCK during the development of grape berries was studied in a range of cultivars. In addition, the presence of PEPCK in grape leaves and the location/abundance of PEPCK in developing grape seeds were investigated. PEPCK was present in the pericarp of all the cultivars of Vitis vinifera studied and in that of the hybrid 420A (Vitis berlandieri × Vitis riparia). By contrast, PPDK was either not present or present at very low abundance. The results strongly indicated that the PEPCK and not the PPDK pathway is the predominant one utilised in gluconeogenesis in the berry pericarp of grape genotypes. Further, the results showed that the abundance of PEPCK increased greatly at the start of ripening in all the cultivars, showing a similar pattern in all of them. PEPCK was not present (or at very low abundance) in grape leaves throughout their development. In developing grape seeds, the results indicated a similar abundance of PEPCK in both the seed coat and the tissues enclosed by it.

BUD FERTILITY OF NEW TABLE GRAPE CULTIVARS AND BREEDING SELECTIONS IN THE SÃO FRANCISCO VALLEY

ABSTRACT Knowledge of bud fertility is an important aid in selection of new cultivars of table grapes with high yield potential. The aim of this study was to determine the sprouting percentage and fertility index of buds of 11 cultivars and table grape breeding selections over five production cycles. The study was carried out at the Bebedouro Experimental Field of Embrapa Semiárido in Petrolina-PE, Brazil, in the period 2013-2015 considering 14 table grape genotypes and 5 production cycles as sources of variation. A randomized block experimental design was used, evaluating sprouting percentage and the mean bud fertility index. A significant effect of the genotype on sprouting was observed only in the first and second production cycles; however, bud fertility exhibited significant interaction between the genotype and the production cycle, and the highest mean values of bud fertility were obtained in the fifth cycle in the 2nd semester of 2015. The cultivars ‘A Dona’, ‘A1105’, ‘BRS Clara’, and Marroo Seedless’ stood out through high bud fertility (mean values from 0.78 to 0.95 bunches/shoot) in all the cycles evaluated, with higher values in the terminal buds of the cane (8th and 9th buds). These results show the yield potential of these new cultivars in the São Francisco Valley region.

Absorption Kinetics and Efflux of Chloride and Sodium in the Roots of Four Grape Genotypes (Vitis L.) Differing in Salt Tolerance

Grapevine is classified as a moderately sensitive plant to salinity. In this study, two sensitive (GhezelUzum and Shirazi) and two tolerant (H6 and Gharashani) grape genotypes, based on screening experiments under salinity, were selected. Hydroponically grown plants were treated with different concentrations of NaCl. Cl− and Na+ contents were significantly increased in different plant organs of all the genotypes. Under salinity, the roots of the tolerant genotypes accumulated higher Cl− content, compared to the sensitive ones. Cl− content in the shoots of sensitive genotypes was threefold higher than the tolerant ones. The absorption kinetics of Cl− and Na+ under salinity was fitted to the Michaelis–Menten equation. Cl− uptake rate in roots of sensitive genotypes was 2.84 times higher than the tolerant ones. And, Na+ uptake ratio was 1.98. There was significant positive correlation between Cl− and Na+ accumulation in all the genotypes under salinity, and the uptake ratio of Na+ was close to 4. Our studied sensitive genotypes showed a higher cytoplasmic and vacuolar Cl− and Na+ values, compared to the tolerant ones. The difference in salt tolerance among the genotypes can be related to different Cl− and Na+ influx, transport and efflux in the sensitive and tolerant genotypes.

Effects of salinity on antioxidant system in ten grape genotypes.

Salinity is an important environmental factor that limits plant growth and production. Grape is classified as salt sensitive plants. The object of this study was to evaluate effects of salinity on membrane lipid peroxidation, antioxidant components, and antioxidative enzymes activity in ten grape genotypes native to the regions around Urmia Salt Lake.Malondialdehyde content and protective enzymes activities in roots and leaves of ten genotypes increased significantly (p≤0.05) under salinity. Salinity had an obvious effect on the accumulation of total phenolics content and induced phenylalanine ammonia-lyase enzyme activity in all genotypes. H6 showed low increases in Malondialdehyde content, also this genotype showed good enzymes activities and total phenolics content and PAL activity. There were significant positive correlations (p≤0.01, r2=0.7) between antioxidative enzyme activities, total phenolics content, and phenylalanine ammonia-lyase activity in the leaves of all genotypes. It seems that H6 showed a higher capacity to tolerate salinity compared to the other genotypes.

Genetic Identification and Conservation of Local Turkish Grapevine (Vitis vinifera L.) Genotypes on the Edge of Extinction

In the second half of the nineteenth century, intensive renovation of vineyards took place due to the losses caused by phylloxera and local varieties were mostly replaced by several worldwide cultivars. Shift in genotypic structure in favor of modern cultivars resulted in the decrease or even disappearance of regionally typical local varieties. A total of sixty five Turkish grape genotypes, including 5 references (four cultivars and one rootstock), were genotyped with 16 SSR and 15 SRAP markers. Sixteen SSR primers generated a total of 60 SSR amplicons in which 43 were polymorphic with 73.4% average polymorphism percentage. A total of 111 well-resolved clear DNA bands were obtained from 15 SRAP primers. Of these bands, 53 were highly polymorphic with an average of 47.74%. Cluster analysis based on pooled marker data generated a well resolved grouping pattern. The analyzed genotypes grouped basing on their geographical belongings. There were many cultivar pairs on the dendrogram most of which occurred between 0.75 and 0.90 levels. SSR and SRAP data revealed a wide genetic variability as well as certain synonyms among the historical grape varieties cultivated for decades in local vineyards lengthwise the mountainous regions of Konya, Karaman and Mersin provinces. All the genotypes have been maintained in a grapevine germplasm glasshouse. Preservation and use of these endangered genotypes will be helpful to avoid genetic erosion and diversity loss in this part of Turkey. Also, the molecular data generated in this study could be of great use in determining the optimal breeding strategies to allow continued progress in grapevine breeding.

Genetic Diversity and Association Study of Aromatics in Grapevine

Monoterpenoid metabolism and aroma compounds are influenced by genetic characteristics. Linalool, α-terpineol, nerol, and geraniol are primary monoterpenoids that have previously been studied in grape (Vitis vinifera) berries. Previous studies were restricted by the lack of relevant studies investigating population structure and the regulatory mechanism underlying monoterpenoid synthesis. In this study, a total of 1133 alleles were amplified, with each locus having on average 6.06 alleles. We also assessed the genetic variability among the genotypes based on 187 microsatellite primer pairs amplified in 96 grape genotypes. The results of the phylogenetic tree analysis showed that the grapevine accessions grouped into five genetic clusters that largely coincided with the recognized species classification and the result of principal coordinates analysis (PCoA). The molecular characterization of these accessions provides insight into genetic diversity, population structure, and linkage disequilibrium (LD) in grapevines. A total of 51 quantitative trait loci (QTLs) were detected that were significantly associated with linalool, α-terpineol, nerol, and geraniol. We found that Deoxyxylulose phosphate synthase (DXS) was located in the region UDV060 on linkage group (LG) 5, whereas Farnesyl diphosphate synthase (FPPS) and Hydroxymethylbutenyl diphosphate reductase (HDR) were located in the VLG19-I-1 and VLG3-A-1 regions, respectively. These novel QTLs will potentially assist in the screening of aroma compounds in grapevines.

Genetic identification and characterization of Armenian grapevine cultivars

Armenia is an important area of crop origins including grapes. The objectives of this study were the molecular characterization of 38 Armenian grape genotypes and the detection of the genetic relationships between the accessions. In total, 164 alleles were obtained at 18 SSRs loci. The number of alleles per locus ranged from 5 to 15 with a mean number of 9.17 alleles per locus. The expected heterozygosity ranged from 0.514 (VVIN73) to 0.90 (VVS2) and the observed heterozygosity from 0.417 (VVIV37) to 0.947 (VVMD7 and VMC1B11). In our research the highest values of polymorphic information content (PIC) were obtained using markers VVS2, VRZAG62 and VRZAG79, while the least informative ones were VVIN73 and VVIB01. A high level of gene diversity was observed between ancient and new bred cultivars. Higher values were recorded for the new grape varieties, (He = 0.792) and lower values for ancient cultivars (He = 0.739). The mean number of alleles (MNA) for all loci per population ranged from 7.39 in ancient to 8,00 in new crosses. A clear separation was observed for the groups of ancient aboriginal cultivars, Vitis vinifera L. xVitis vinifera L. and Vitis vinifera L. x Vitis amurensis Rupr . crosses, which were bred in Armenia and seedless cultivars. Very close relationships with high similarity were determined for 5 pairs of cultivars. Two cases of possible homonymy were also detected. Our results are the basis for future MAS selection and target breeding.

Development of an in vitro Dual Culture System for Grapevine and Xiphinema index as a Tool for Virus Transmission

Grapevine fanleaf virus (GFLV) is a nepovirus that is transmitted to grapevines by the ectoparasitic nematode Xiphinema index. GFLV causes severe losses in yield and quality in viticulture worldwide. Presently, laborious and time-consuming field trials or greenhouse tests are necessary for screening putative GFLV resistance in new grape genotypes developed in breeding programmes. We developed an in vitro dual culture system for grapevines and nematode vectors that requires less time and space than inoculation experiments done in the greenhouse. Virus infection of in vitro grapevines was investigated using immunocapture-reverse transcriptase-polymerase chain reaction (IC-RT-PCR) analysis. The development of root galls induced by feeding nematodes on in vitro grapevines was also analysed. Virus infection in grapevines in the dual culture with viruliferous nematodes was detected six weeks post-inoculation. Root galls were always absent from parasitised in vitro grapevines with detectable virus infection, whereas they developed on some parasitised, but virus-negative tested grapevines. Therefore, root galls cannot be used as a reliable indicator for parasitism and virus transmission.

Consumer Acceptability of Fresh-Market Muscadine Grapes.

The objective of this research was to investigate the acceptability of muscadine grape (Vitis rotundifolia) genotypes (cultivars and selections) and to correlate overall liking to other quality measurements to determine the main drivers of liking. Twenty-two genotypes grown at the Univ. of Georgia-Tifton Campus were evaluated. Four retail commercial grape genotypes (Vitis vinifera and "Concord") were also evaluated for comparison. Panelists familiar with muscadine grapes used the hedonic general labeled magnitude scale (HgLMS, -100 = strongest disliking of any kind ever experienced, +100 = strongest liking of any kind ever experienced) to rate overall liking and the liking of appearance, flavor, pulp texture, and skin texture. Puncture testing was done to assess grape berry texture, and compositional attributes soluble solids and pH were also measured. The sensory results indicated that the grapes were variable with overall liking scores from 12.2 to 39.6. The factors highly correlated with overall liking scores were muscadine flavor, pulp and skin liking, while a significant negative correlation was found between skin liking and skin texture and mechanical texture measures. The muscadine grapes with the highest overall liking scores were Ga. 5-1-34 and Ga. 2-8-21. Principal component analysis confirmed that grapes with a thinner skin and a higher pH tended to group around overall liking and flavor points. These results indicate that even among panelists familiar with muscadine grapes, skin thickness is a negative characteristic. Breeding for thinner skins may be a positive step in muscadines gaining a more widespread appeal in the fresh fruit market.

In Depth Proteome Analysis of Ripening Muscadine Grape Berry cv. Carlos Reveals Proteins Associated with Flavor and Aroma Compounds.

Ripening in nonclimacteric fruits such as grape involves complex chemical changes that have a profound influence on the accumulation of flavor and aroma compounds distinct to a particular grape genotype. In this study, proteome characterization of wine type bronze muscadine grape (Vitis rotundifolia cv. Carlos), primarily grown in the Southeastern United States was performed during berry ripening. Stage-specific protein expression was obtained among different stages of berries. Differential analysis showed the expression of 522 proteins that regulate diverse biological processes and metabolic pathways. Of these, 30 proteins are associated with the production of key phenolic compounds, whereas 25 are associated with the production of muscadine aroma compounds. These proteins are involved in the phenylpropanoid pathway, terpene synthesis, fatty acid derived volatiles and esters that affect muscadine berry flavor and aroma characteristics. Further, gene expression analysis during ripening validated the expression pattern of 12 proteins. Catechin, epicatechin, and four stilbenes were quantified to correlate observed proteome changes. This study not only revealed biochemical changes during muscadine berry ripening but also offers indicators for marker-assisted breeding to enhance organoleptic properties of muscadine grape to improve its flavor and aroma properties.

Effects of Salinity on Plant Hormones Genes in Grape

The aim of this study was to investigate the effects of NaCl on expression of five genes—related to salinity tolerance—in grape (Vitis L.). Based on our screening study on 18 grape genotypes, ‘H6’ and ‘Gharashani’ (tolerant) and ‘Shirazi’ and ‘GhezelUzum’ (sensitive) were selected for molecular analysis. Plants were treated with 50 mM NaCl as a critical concentration that is not lethal for grapevine plants. Growth parameters reduced under salinity, that decrease in sensitive genotypes was higher than tolerant ones. The expression of VvRIP1 (abscisic acid receptor) increased in leaves of sensitive and decreased in tolerant genotypes. Also the expression of VvGID1L1 (a gibberellin receptor) was similar to VvIAA5 (an auxin-induced protein) under salinity, both of them upregulated in roots of tolerant and down regulated in sensitive genotypes. Our findings showed a significant difference between tolerant and sensitive genotypes.