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THE proposed value-added tax bill is a departure from the globally VAT approved parameters. VAT requires simplified procedures, lesser involvement of the Federal Board of Revenue in day-today affairs and [...]

Increasing salinization is a threat to viticultural production as the quantity and quality of irrigation water decreases. Grapevines are particularly sensitive to chloride ions, but some wild species of VitisL. have been found to restrict chloride uptake. Therefore, it is possible to breed rootstocks that prevent chloride from reaching the leaves or fruit, where buildup of the ion can reduce photosynthetic capacity and affect fruit and wine quality. A previously developed greenhouse screen for chloride exclusion, which mimics field results, was applied to 325 accessions of 14 Vitisspecies collected from the southwestern United States and Mexico. While the trait was not clearly associated with any particular species or geographic region, promising chloride‐excluding accessions were identified. Vitis girdianaMunson from southern Nevada and V. X doanianaMunson ex Viala from the border of Texas and Oklahoma both consistently restricted chloride uptake in comparison to 140 Ruggeri (140 Ru), a known salt excluder. In addition, many accessions of V. girdianafrom southern Nevada took up less than half the concentration of chloride in the roots as compared with 140 Ru. The prevalence of the chloride exclusion trait across multiple genetic backgrounds indicates that this collection may contain multiple sources for chloride exclusion in grape. This screen is an important first step in the characterization of Vitisrootstock breeding material from the southwestern United States and Mexico.

Abstract: Recombination rate data are presented for three populations of grape based on framework genetic linkage maps developed with simple-sequence repeat markers. These linkage maps were constructed from different Vitis species and represent three genetic backgrounds. The first population is pure Vitis vinifera, derived from a cross of the European cultivars Riesling and Cabernet Sauvignon. The second is an interspecific cross between two commercially used rootstock cultivars of different North American Vitis species parentage, Ramsey (Vitis champinii) and Riparia Gloire (Vitis riparia). The third population, D8909-15 (Vitis rupestris × (Vitis arizonica/Vitis girdiana form)) × F8909-17 (V. rupestris × (V. arizonica/Vitis candicans form)), is an F1 from two half-sibs. Genome-wide and chromosome-wide recombination rates varied across the three populations and among the six Vitis parents. Global recombination rates in the parents of the third F1 population, with a complex Vitis background, were significantly reduced. In the first and third populations, the recombination rate was significantly greater in the male parent. Specific genome locations with frequent heterogeneity in recombination were identified, suggesting that recombination rates are not equal across the Vitis genome. The identification of regions with suppressed or high recombination will aid grape breeders and geneticists who rely on recombination events to introgress disease resistance genes from the genomes of wild Vitis species, develop fine-scale genetic maps, and clone disease resistance genes.

The North American muscadine grape (Muscadinia rotundifolia Small) is a valuable source of resistance to powdery mildew [Uncinula necator (Schw.) Burr], root-knot nematode (Meloidogyne Goeldi), dagger nematode (Xiphinema index Thorne and Allen), grape phylloxera (Daktulosphaira vitifoliae Fitch), and Pierce's disease (Xylella fastidiosa Wells et al.). Efforts to breed muscadine grapes commenced in the early 1900s and have generated a large number of cultivars and a limited number of hybrids with Vitis vinifera L. and other Vitis L. species. Collections of this germplasm are currently maintained with accession identity based on declared identity when collected, breeding records, and comparisons of morphological traits. This study reports on the first use of DNA-based simple sequence repeat (SSR) marker profiles to authenticate M. rotundifolia cultivars and hybrids. A total of 57 accessions [39 M. rotundifolia cultivars, 3 V. vinifera cultivars, 3 Vitis spp. hybrids, and 12 V. vinifera x M. rotundifolia (VR) hybrids] from collections at the U.S. Department of Agriculture National Clonal Germplasm Repository and the University of California (Davis) Department of Viticulture and Enology were analyzed with 14 SSR markers. The fingerprint profiles were used to verify published breeding records of 31 M. rotundifolia cultivars and hybrids by comparing the shared alleles of parents and progeny. Marker data indicated that four cultivars were incorrectly identified; their alleles did not match respective parent/progeny relationships at more than five loci. Two M. rotundifolia accessions had the same fingerprint profile as a third accession at all 14 markers, implicating a likely planting error. The M. rotundifolia cultivars exhibited 88 unique alleles that were not present in a database of more than 600 V. vinifera cultivars. [ABSTRACT FROM AUTHOR]

Background: Introgressive hybridization can reassort genetic variants into beneficial combinations, permitting adaptation to new ecological niches. To evaluate evolutionary patterns and dynamics that contribute to introgression, we investigate six wild Vitisspecies that are native to the Southwestern United States and useful for breeding grapevine (V. vinifera) rootstocks. Results: By creating a reference genome assembly from one wild species, V. arizonica, and by resequencing 130 accessions, we focus on identifying putatively introgressed regions (pIRs) between species. We find six species pairs with signals of introgression between them, comprising up to ~ 8% of the extant genome for some pairs. The pIRs tend to be gene poor, located in regions of high recombination and enriched for genes implicated in disease resistance functions. To assess potential pIR function, we explore SNP associations to bioclimatic variables and to bacterial levels after infection with the causative agent of Pierce’s disease (Xylella fastidiosa). pIRs are enriched for SNPs associated with both climate and bacterial levels, suggesting that introgression is driven by adaptation to biotic and abiotic stressors. Conclusions: Altogether, this study yields insights into the genomic extent of introgression, potential pressures that shape adaptive introgression, and the evolutionary history of economically important wild relatives of a critical crop.

Grape powdery mildew (PM), caused by the biotrophic ascomycete Erysiphe necator, is a devastating fungal disease that affects most Vitis vinifera cultivars. We have previously identified a panel of V. vinifera accessions from Central Asia with partial resistance to PM that possess a Ren1-like local haplotype. In this study, we show that in addition to the typical Ren1-associated late post-penetration resistance, these accessions display a range of different levels of disease development suggesting that alternative alleles or additional genes contribute to determining the outcome of the interaction with the pathogen. To identify potential Ren1-dependent transcriptional responses and functions associated with the different levels of resistance, we sequenced and analyzed the transcriptomes of these Central Asian accessions at two time points of PM infection. Transcriptomes were compared to identify constitutive differences and PM-inducible responses that may underlie their disease resistant phenotype. Responses to E. necator in all resistant accessions were characterized by an early up-regulation of 13 genes, most encoding putative defense functions, and a late down-regulation of 32 genes, enriched in transcriptional regulators and protein kinases. Potential Ren1-dependent responses included a hotspot of co-regulated genes on chromosome 18. We also identified 81 genes whose expression levels and dynamics correlated with the phenotypic differences between the most resistant accessions ‘Karadzhandahal’, DVIT3351.27, and O34-16 and the other genotypes. This study provides a first exploration of the functions associated with varying levels of partial resistance to PM in V. vinifera accessions that can be exploited as sources of genetic resistance in grape breeding programs.