Date of Award

Winter 2022

Project Type

Thesis

Program or Major

Biological Sciences

Degree Name

Master of Science

First Advisor

Rebecca G. Sideman

Second Advisor

Anissa Poleatewich

Abstract

Grapes are grown worldwide to produce wine, grape juice and are also popular as fresh table grapes or dried raisins. Due to their nutritional value and importance in the multibillion-dollar wine industry, grapes are considered the most commercially important berry crop. Grape production has primarily concentrated on European wine grapes, Vitis vinifera, in the dry, hot Mediterranean and Central Asian climates. V. vinifera is not cold tolerant enough to endure winter temperatures below -15°C. The introduction of several interspecific hybrids (of both wine and table grape) cultivars in the 20th century and selection of a training system has helped propel the expansion of grapevine cultivation in cooler climates such as the Northeastern US and upper midwestern US states. Training and trellising systems are part of viticultural practices that influence many aspects of grapevine growth and productivity. Especially in cool climates like New Hampshire, choosing an appropriate training system will provide the grapevines with good exposure of leaves and berries to sunlight leading to fruits with improved berry composition and higher levels of sugar accumulation as well as increased concentrations of anthocyanins and phenolic compounds. However, there is limited research on the impact of training systems on cold-hardy table grapevine physiology and biochemistry. To address these knowledge gaps research was conducted at the UNH Woodman Horticultural Research Farm in Durham, NH, where cold-hardy grape varieties are growing on two different training systems. Mars and Canadice grape varieties grown on vertical shoot positioning (VSP) and Munson (M) training systems were used. Grapevine physiology and biochemistry were followed throughout three growing seasons using destructive and non-destructive methods to monitor grapevine health. Additionally, considering the current need for alternative environmentally friendly fungicides, plant material from these cold-hardy grape cultivars was tested for their putative antifungal properties.

The objectives of this study were to: (1) Determine the physiological and biochemical parameters of Canadice and Mars cold-hardy grape varieties growing on vertical shoot positioning (VSP) and Munson training systems, and (2) Investigate the putative antifungal activity of field-collected grapevine leaves and cell suspension cultures obtained from Canadice and Mars grapevines against Botrytis cinerea. I hypothesized that the training system would influence the SPAD measurements, spectral indices (normalized difference vegetation index, red edge inflection point, moisture stress index, and phenology index), and gas exchange measurements (intercellular carbon dioxide concentration, stomatal conductance, net photosynthesis, transpiration rate, vapor pressure deficit, and water use efficiency) of Mars and Canadice leaves growing on two different training systems. I also hypothesized that the training system would have an effect on the amount of leaf photosynthetic pigments, leaf, juice, and skin metabolomes, titratable acidity and soluble solid contents of Canadice and Mars growing on two different training systems (Chapter 2). I hypothesized that field-collected leaves and cell suspension cultures established from Canadice and Mars grape varieties would contain compounds with antifungal activity against B. cinerea (Chapter 3).

For objective 1, physiological parameters were measured with SPAD, spectral analysis, and gas exchange analysis on grapevine leaves throughout three growing seasons (2019, 2020, and 2021). Specifically, I determined the SPAD measurements, the spectral indices normalized difference vegetation index (NDVI), red edge inflection point (REIP), moisture stress index (MSI) and phenology index, and gas exchange measurements to determine intercellular carbon dioxide concentration (Ci), stomatal conductance (gs), vapor pressure deficit (VPD), net photosynthesis (A), transpiration (E), and water use efficiency (WUE). While no differences were found regarding training systems alone, there was a significant interaction of training system with time, suggesting that training system had different effects at different times. For the biochemical parameters, the same leaves that were used to perform SPAD measurements were used to analyze photosynthetic pigments and proton based nuclear magnetic resonance (1H-NMR spectroscopy)-based metabolomics. Consistent with the results of physiological parameters, no differences were found for photosynthetic pigments - chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids - between training systems, but the training system had different effects at different time points. The leaf metabolites studied using 1H-NMR spectroscopy coupled with multivariate statistical analysis did not distinguish samples based on training systems, but sample separation occurred based on phenological stages. The compounds identified showed variations between flowering, veraison, and harvest. Namely, sucrose gradually increased from flowering to harvest. Additionally, the 1H-NMR spectroscopy-based metabolome of grape juice was investigated in grape berries collected from veraison to harvest. Various kinds of metabolites were identified. Fructose, glucose, alanine, threonine, myo-Inositol, and 3-hydroxybutyrate were all shown to increase from veraison to harvest. The amount of fructose and glucose increased over time (between veraison and harvest) and are indicators of berry ripeness. Furthermore, at harvest, grape titratable acidity and total soluble solid content were determined, and berry skin composition was investigated using ultra performance liquid chromatography-mass spectrometry (UPLC-MS) analysis. Distinct sets of metabolites were identified in Mars and Canadice skin samples and were dependent on the training system.

For my objective 2, I investigated the putative antifungal activity of Mars- and Canadice-derived products, specifically field-collected grapevine senescent leaves and cell suspension cultures, against B. cinerea. The aim was to gather knowledge that could lead to the development of new botanical fungicides that could be used as an alternative to synthetic fungicides for disease management in vineyards. This approach could contribute to sustainable management practices in the long term. Using grapevine debris (such as canes, wood, and leaves) from V. vinifera to suppress B. cinerea and other plant pathogens has been successfully demonstrated. However, there is limited research evaluating secondary metabolites with antifungal properties from cold-hardy grapevines. Our results show that grapevine-derived extracts have antifungal activity in vitro and in detached berry experiments when challenged with B. cinerea, but the antifungal activity was not translated to in planta experiments. The metabolic profiling of senescent leaves and cell suspension cultures of Mars and Canadice identified an array of compounds, including some reported to have antimicrobial properties. Given the list of compounds that have been identified in cold-hardy grapevine-derived products, future work should examine these unique compounds present in the senescent leaves and cell cultures under controlled experimental conditions. While our results indicated that Mars- and Canadice-derived products have antifungal activity, the materials used in this study were crude extracts. Future studies should focus on using finer grapevine-products to test the efficacy against B. cinerea, not only in vitro, but also using pilot-scale greenhouse trials, and vineyard trials.

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