Sonet Van Zyl

Sonet Van Zyl


Research Focus & Metrics

Academic Career Length

4Years (2023-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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6 April 2023 in Climate
Verified
Journal Article
Open access
PDF file
QSQun Sun
Qun Sun
Gabriel GrancoGabriel Granco
Gabriel Granco
LGLeah Groves
Leah Groves
JVJully Voong
Jully Voong
SZSonet Van Zyl
Sonet Van Zyl
Climate change is a critical challenge for the global grape and wine industry, as it can disrupt grapevine growth, production, and wine quality. Climate change could influence the cost-effectiveness and growth of the wine industry in different wine regions since grapevine development is deeply dependent on weather (short-term) and climate (long-term) conditions. Innovation and new technologies are needed to meet the challenge. This review article addresses the impact of climate change on grapevines, such as vine phenology, pest and disease pressure, crop load, and grape and wine composition. It also reviews recent advances in the areas of viticultural manipulation and relevant technologies to potentially reduce the impact of climate change and help growers improve grape quality. Remote sensing is used for vineyard microclimate monitoring; thermal sensors combined with UAVs, aircraft, or satellites are used for water management; soil electrical conductivity sensors have been developed for soil mapping. Viticultural manipulations, such as regulated deficit irrigation for water use efficiency and berry-ripening delay for growing quality fruit, are also discussed. The review assesses future directions for further technological development, such as soil and vine water monitoring devises, precision viticulture, and artificial intelligence in vineyards.

1 January 2023 in Plant Health Progress
Verified
Journal Article
Closed access
CSCameron V. Saunders
Cameron V. Saunders
SZSonet Van Zyl
Sonet Van Zyl
RNRachel Naegele
Rachel Naegele
Five isolates of Xylella fastidiosa subsp. fastidiosa were evaluated for virulence differences using the grape cultivar Cabernet Sauvignon. Significant variation in virulence was observed among isolates. Two isolates representing high and moderate virulence in grape were used for evaluating susceptibility on 21 grape lines (cultivars and breeding lines). Lines showed significant differences in symptom development and bacterial populations when inoculated with one of two isolates. Table grape cultivars Scarlet Royal, Solbrio, and Red Globe were among the cultivars with the highest disease symptoms and bacterial populations, whereas Flame Seedless showed moderate or low symptoms and had lower bacterial populations in this study than most other commercial table grape cultivars. Sources of Pierce's disease resistance or tolerance commonly used in breeding programs showed few symptoms when inoculated with either isolate, but levels of bacteria within the plant varied. A new source of Pierce's disease resistance/tolerance, IAC 572, was identified.

20 April 2023 in Plants
Verified
Journal Article
Open access
PDF file
SSStephan Sommer
Stephan Sommer
MSMarnelle Salie
Marnelle Salie
EGEsteban Garcia
Esteban Garcia
ARAnthony Reyes
Anthony Reyes
SESteven C. Ebersole
Steven C. Ebersole
SZSonet Van Zyl
Sonet Van Zyl
Plants accumulate different types of phenolic material in their tissue as a response to biotic as well as abiotic stress. Monomeric polyphenols and smaller oligomers can serve as protection against ultraviolet radiation or prevent oxidative tissue damage, while larger molecules such as tannins can be the plant’s reaction to an infection or physical damage. Therefore, characterization, profiling, and quantification of diverse phenolics can provide valuable information about the plant and the stress status at any given time. A method was developed that allows the extraction of polyphenols and tannins from leaf tissue, followed by fractionation and quantification. Extraction was performed with liquid nitrogen and 30% acetate-buffered ethanol. The method was tested with four cultivars under varying extraction conditions (solvent strength and temperature) and showed great improvements of the chromatography that would otherwise be impacted by tannins. The separation of tannins from smaller polyphenols was achieved by bovine serum albumin precipitation and resuspension in a urea-triethanolamine buffer. Tannins were reacted with ferric chloride and analyzed spectrophotometrically. Monomeric non-protein-precipitable polyphenols were then analyzed via HPLC-DAD from the supernatant of the precipitation sample. This way, a more complete spectrum of compounds can be analyzed from the same plant tissue extract. With the fractionation suggested here, hydroxycinnamic acids and flavan-3-ols can be separated and quantified with good accuracy and precision. Possible applications include the assessment of plant stress and response monitoring using the total concentrations of polyphenols and tannins, as well as the ratios between those compound classes.