Ontogenic Resistance to Uncinula necator Varies by Genotype and Tissue Type in a Diverse Collection of Vitis spp.

Berries of grapevine (Vitis spp.) have a limited window of susceptibility to Uncinula necator, the causal agent of grapevine powdery mildew, until the onset of ontogenic resistance approximately 2 to 3 weeks postbloom. This phenomenon has been demonstrated in several cultivars of V. vinifera and in V. labruscana ‘Concord’, which all exhibited a similar duration of susceptibility. To identify genetic variation for ontogenic resistance, we screened a diverse collection of Vitis species and interspecific hybrids maintained in the USDA-ARS cold-hardy Vitis germplasm collection in Geneva, NY. Of the 79 genotypes whose fruit clusters were screened for susceptibility to powdery mildew under field conditions, 50 exhibited a high level of constitutive resistance to powdery mildew and did not develop more than trace levels of disease when inoculated, irrespective of the stage of berry development at inoculation. Twenty-four genotypes exhibited a significant gain of resistance as berries aged. This ontogenic resistance was conserved across four species and several interspecific hybrids of Vitis spp., although the timing of the onset of ontogenic resistance varied by genotype. The mechanism of ontogenic resistance was examined for four genotypes. Similar to previous studies, ontogenic resistance greatly reduced the incidence of successful penetration. Despite the broad conservation of ontogenic resistance across species, one genotype (V. rupestris ‘R-65-44’) remained susceptible past the onset of ripening, over 1 month later than reported previously for V. vinifera and V. labruscana. Variation in the resistance phenotype was observed among the rachis, pedicels, and berries within clusters of the majority of genotypes studied. The genetic variation in ontogenic resistance, in particular the discovery of a genotype in which berries remain susceptible as they mature, will facilitate further study of the inheritance and molecular basis of ontogenic resistance.

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Effects of Diffuse Colonization of Grape Berries by Uncinula necator on Bunch Rots, Berry Microflora, and Juice and Wine Quality

Phytopathology ◽

10.1094/phyto-97-10-1356 ◽

2007 ◽

Vol 97 (10) ◽

pp. 1356-1365 ◽

Cited By ~ 35

Author(s):

David M. Gadoury ◽

Robert C. Seem ◽

Wayne F. Wilcox ◽

Thomas Henick-Kling ◽

Lorenza Conterno ◽

...

Keyword(s):

Powdery Mildew ◽

Severe Infection ◽

Uncinula Necator ◽

Wine Quality ◽

High Quality ◽

Grape Berries ◽

Naked Eye ◽

Ontogenic Resistance ◽

High Level ◽

Spoilage Microorganisms

Production of grape (principally cultivars of Vitis vinifera) for high-quality wines requires a high level of suppression of powdery mildew (Uncinula necator syn. Erysiphe necator). Severe infection of either fruit or foliage has well-documented and deleterious effects upon crop and wine quality. We found that berries nearly immune to infection by U. necator due to the development of ontogenic resistance may still support diffuse and inconspicuous mildew colonies when inoculated ≈3 weeks post-bloom. Fruit with diffuse mildew colonies appear to be healthy and free of powdery mildew in late-season vineyard assessments with the naked eye. Nonetheless, presence of these colonies on berries was associated with (i) elevated populations of spoilage microorganisms; (ii) increased evolution of volatile ethyl acetate, acetic acid, and ethanol; (iii) increased infestation by insects known to be attracted to the aforementioned volatiles; (iv) increased rotting by Botrytis cinerea; and (v) increased frequency of perceived defects in wines prepared from fruit supporting diffuse powdery mildew colonies. Prevention of diffuse infection requires extending fungicidal protection until fruit are fully resistant to infection. Despite a perceived lack of improvement in disease control due to the insidious nature of diffuse powdery mildew, potential deleterious effects upon crop and wine quality thereby would be avoided.

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Effects of Ontogenic Resistance upon Establishment and Growth of Uncinula necator on Grape Berries

Phytopathology ◽

10.1094/phyto.2003.93.5.556 ◽

2003 ◽

Vol 93 (5) ◽

pp. 556-563 ◽

Cited By ~ 45

Author(s):

Andrea Ficke ◽

David M. Gadoury ◽

Robert C. Seem ◽

Ian B. Dry

Keyword(s):

Powdery Mildew ◽

Colony Growth ◽

Similar Degree ◽

Uncinula Necator ◽

Disease Development ◽

Phenological Stage ◽

Appressorium Formation ◽

Hyphal Length ◽

Grape Berries ◽

Ontogenic Resistance

Grape berries become resistant to powdery mildew early in development and are nearly immune to infection within 4 weeks after bloom. In this study, ontogenic resistance did not reduce attachment, germination, or appressorium formation of Uncinula necator on 3- to 4-week-old berries of Vitis vinifera ‘Chardonnay’ or 3-week-old berries of V. labruscana ‘Concord’. Pathogen ingress halted at the cuticle before formation of a penetration pore. As berries aged, hyphal elongation and colony growth slowed until finally no secondary hyphae formed on fully resistant berries. More appressoria formed per unit of hyphal length as berries aged, indicating that failure to penetrate older berries led to increased attempts to penetrate resistant fruit. Additionally, hyphae within the colonies began to die as berries aged. Finally, the number of degree-hours between germination and sporulation of the colony (latent period) increased and sporophore density decreased with berry age at time of inoculation. Thus, ontogenic resistance both slows, and eventually halts disease development on grape berries, and limits the likelihood of spread by reducing absolute supply of conidia and delaying their formation. It furthermore has a consistent, stable, and predictable impact on grape powdery mildew and operates in a similar fashion and to a similar degree in both V. labruscana and V. vinifera, although at a slightly earlier phenological stage in V. labruscana.

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Ontogenic Resistance to Powdery Mildew in Grape Berries

Phytopathology ◽

10.1094/phyto.2003.93.5.547 ◽

2003 ◽

Vol 93 (5) ◽

pp. 547-555 ◽

Cited By ~ 86

Author(s):

David M. Gadoury ◽

Robert C. Seem ◽

Andrea Ficke ◽

Wayne F. Wilcox

Keyword(s):

Disease Management ◽

Powdery Mildew ◽

Critical Period ◽

Fruit Set ◽

Pinot Noir ◽

Soluble Solids ◽

Uncinula Necator ◽

Grape Berries ◽

Ontogenic Resistance ◽

Resistance To Infection

Berries of Vitis vinifera are reported to be susceptible to infection by Uncinula necator until soluble solids levels (brix) reach 8%, and established colonies are reported to sporulate until brix reach 15%. However, our analysis of disease progress on fruit of selected V. vinifera cultivars indicated that severity became asymptotic several weeks earlier in fruit development. When mildew-free fruit clusters of V. vinifera ‘Chardonnay’, ‘Riesling’, ‘Gewürztraminer’, and ‘Pinot Noir’ were inoculated at stages ranging from prebloom to 6 weeks postbloom, only fruit inoculated within 2 weeks of bloom developed severe powdery mildew. Substantial ontogenic resistance to infection was expressed in fruit nearly 6 weeks before fruit brix reached 8% and over 2 months before they reached 15%. Rachises of ‘Chardonnay’ and ‘Riesling’ fruit clusters developed severe powdery mildew when inoculated at bloom, and disease increased steadily over the next 60 days. The rachis of fruit clusters inoculated 31 days after bloom developed only trace levels of powdery mildew. Berry weight of all four cultivars at harvest was reduced when fruit clusters were inoculated at bloom or 16 days postbloom, primarily by splitting, rotting, and dehydration of mildewed berries, but the weight of later-inoculated berries was not reduced. Inoculation of berries just as ontogenic resistance increased markedly, approximately 3 to 4 weeks postbloom, resulted in the development of inconspicuous, diffuse, non-sporulating mildew colonies on berries, sometimes associated with a network of necrotic epidermal cells. Rather than a protracted and relatively static period of berry susceptibility lasting 3 months, fruit of V. vinifera appear to acquire ontogenic resistance rapidly after fruit set. A refocusing of disease management on this critical period of high fruit susceptibility should greatly improve the efficacy of fungicides directed against powdery mildew.

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The effects of canopy management practices on fruit quality of northern-hardy interspecific hybrids of Vitis spp.

10.31274/etd-180810-3460 ◽

2014 ◽

Author(s):

Dylan Paul Rolfes

Keyword(s):

Fruit Quality ◽

Interspecific Hybrids ◽

Management Practices ◽

Vitis Spp ◽

Canopy Management

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Genetic Analysis of Chinese Cucumber Collections in the U.S. National Germplasm Collection

HortScience ◽

10.21273/hortsci.33.3.534e ◽

1998 ◽

Vol 33 (3) ◽

pp. 534e-534 ◽

Cited By ~ 1

Author(s):

J. Staub ◽

Felix Sequen ◽

Tom Horejsi ◽

Jin Feng Chen

Keyword(s):

Genetic Diversity ◽

Principal Component Analysis ◽

Genetic Variation ◽

Genetic Analysis ◽

Allelic Variation ◽

Germplasm Collection ◽

Principal Component ◽

Isozyme Loci ◽

National Plant Germplasm System ◽

The U.S

Genetic variation in cucumber accessions from China was assessed by examining variation at 21 polymorphic isozyme loci. Principal component analysis of allelic variation allowed for the depiction of two distinct groupings of Chinese accessions collected in 1994 and 1996 (67 accessions). Six isozyme loci (Gpi, Gr, Mdh-2, Mpi-2, Pep-gl, and Pep-la) were important in elucidating these major groups. These groupings were different from a single grouping of Chinese 146 accessions acquired before 1994. Allelic variation in Chinese accessions allowed for comparisons with other accessions in the U.S. National Plant Germplasm System (U.S. NPGS) collection grouped by continent and sub-continent. When Chinese accessions taken collectively were compared with an array of 853 C. sativus U.S. NPGS accessions examined previously, relationships differed between accessions grouped by country or subcontinent. Data indicate that acquisition of additional Chinese and Indian cucumber accessions would be strategically important for increasing genetic diversity in the U.S. NPGS cucumber collection.

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Content of trans-resveratrol in leaves and berries of interspecific grapevine (Vitis sp.) varieties

Czech Journal of Food Sciences ◽

10.17221/238/2008-cjfs ◽

2009 ◽

Vol 26 (Special Issue) ◽

pp. S13-S17 ◽

Cited By ~ 4

Author(s):

P. Bábíková ◽

N. Vrchotová ◽

J. Tříska ◽

M. Kyseláková

Keyword(s):

Powdery Mildew ◽

Downy Mildew ◽

Plasmopara Viticola ◽

Fungal Diseases ◽

Uncinula Necator ◽

Botryotinia Fuckeliana

The aim of this project was to study changes in the content of trans-resveratrol in berries and leaves of grapevine (Vitis sp.) infested by fungal diseases, especially by Botryotinia fuckeliana Whetzel, called as grey mildew, Plasmopara viticola (Berk. & M.A. Curtis) Berl & De Toni, called downy mildew and Uncinula necator (Schw.) Burr, called powdery mildew. In our experiments two white and two blue varieties were used. Contents of trans-resveratrol were determined in healthy and infested leaves and in healthy berries. Infested leaves of white varieties contained more trans-resveratrol than those of blue varieties. The content of trans-resveratrol in berries was lower than that in leaves.

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POPULATION GENETICS OF ALLOZYME VARIATION IN NEUROSPORA INTERMEDIA

Genetics ◽

10.1093/genetics/80.4.785 ◽

1975 ◽

Vol 80 (4) ◽

pp. 785-805

Author(s):

P T Spieth

Keyword(s):

Genetic Variation ◽

Vegetative Reproduction ◽

Vascular Plant ◽

Natural Populations ◽

Allozyme Variation ◽

Regular Feature ◽

Local Populations ◽

Neurospora Intermedia ◽

Pattern Of Variation ◽

High Level

ABSTRACT Electrophoretically detectable variation in the fungus Neurospora intermedia has been surveyed among isolates from natural populations in Malaya, Papua, Australia and Florida. The principal result is a pattern of genetic variation within and between populations that is qualitatively no different than the well documented patterns for Drosophila and humans. In particular, there is a high level of genetic variation, the majority of which occurs at the level of local populations. Evidence is presented which argues that N. intermedia has a population structure analogous to that of an annual vascular plant with a high level of vegetative reproduction. Sexual reproduction appears to be a regular feature in the biology of the species. Substantial heterokaryon function seems unlikely in natural populations of N. intermedia. Theoretical considerations concerning the mechanisms underlying the observed pattern of variation most likely should be consistent with haploid selection theory. The implications of this constraint upon the theory are discussed in detail, leading to the presentation of a model based upon the concept of environmental heterogeneity. The essence of the model, which is equally applicable to haploid and diploid situations, is a shifting distribution of multiple adaptive niches among local populations such that a given population has a small net selective pressure in favor of one allele or another, depending upon its particular distribution of niches. Gene flow among neighboring populations with differing net selective pressures is postulated as the principal factor underlying intrapopulational allozyme variation.

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Applying MRI Intensity Normalization on Non-Bone Tissues to Facilitate Pseudo-CT Synthesis from MRI

Diagnostics ◽

10.3390/diagnostics11050816 ◽

2021 ◽

Vol 11 (5) ◽

pp. 816

Author(s):

Kuei-Yuan Hou ◽

Hao-Yuan Lu ◽

Ching-Ching Yang

Keyword(s):

Mean Value ◽

Tissue Type ◽

Routine Practice ◽

Intensity Level ◽

Mean Values ◽

Conversion Model ◽

Ratio Image ◽

Abdominal Mri ◽

High Level ◽

Intensity Normalization

This study aimed to facilitate pseudo-CT synthesis from MRI by normalizing MRI intensity of the same tissue type to a similar intensity level. MRI intensity normalization was conducted through dividing MRI by a shading map, which is a smoothed ratio image between MRI and a three-intensity mask. Regarding pseudo-CT synthesis from MRI, a conversion model based on a three-layer convolutional neural network was trained and validated. Before MRI intensity normalization, the mean value ± standard deviation of fat tissue in 0.35 T chest MRI was 297 ± 73 (coefficient of variation (CV) = 24.58%), which was 533 ± 91 (CV = 17.07%) in 1.5 T abdominal MRI. The corresponding results were 149 ± 32 (CV = 21.48%) and 148 ± 28 (CV = 18.92%) after intensity normalization. With regards to pseudo-CT synthesis from MRI, the differences in mean values between pseudo-CT and real CT were 3, 15, and 12 HU for soft tissue, fat, and lung/air in 0.35 T chest imaging, respectively, while the corresponding results were 3, 14, and 15 HU in 1.5 T abdominal imaging. Overall, the proposed workflow is reliable in pseudo-CT synthesis from MRI and is more practicable in clinical routine practice compared with deep learning methods, which demand a high level of resources for building a conversion model.

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