Effects of the Enzyme Inhibitor Prohexadione-calcium on Hops Determined by LC-TOF-MS
Item
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Title
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Effects of the Enzyme Inhibitor Prohexadione-calcium on Hops Determined by LC-TOF-MS
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Identifier
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d_2009_2013:20586ccdf34c:10897
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identifier
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11185
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Creator
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Kavalier, Adam Richard,
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Contributor
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Edward J. Kennelly
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Date
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2011
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Language
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English
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Publisher
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City University of New York.
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Subject
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Plant sciences | Biochemistry | flavonoids | hops | Humulus lupulus | prohexadione | terpenophenolics
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Abstract
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Humulus lupulus L. (hops) is an agricultural crop valued for its inflorescences, commonly known as hop cones, which produce a diverse collection of secondary metabolites. Hop cones are most valued for their terpenophenolic contents, which are essential to beer production, and the subject of biomedical research. We studied two hop cultivars, Willamette and Zeus, over five stages of development, which were characterized by detailed flower morphology, gross cone measurements, and phytochemical quantitation. By combining morphological observations with phytochemical quantitation we produced an index to inform our developmentally dependent experiments. In order to understand these developmental processes and in an attempt to induce agronomically positive effects, we perturbed hop morphological and phytochemical development using enzyme inhibition.;Prohexadione-calcium (Pro-Ca) is a known inhibitor of 2-oxoglutaric acid dependent dioxygenases present in the flavonoid, gibberellic acid, and ethylene biosynthetic pathways. We treated hops with Pro-Ca at each of the five time-points over two seasons; these time-points were later characterized as five developmental stages. Pro-Ca treatment induced significant increases in terpenophenolic content by 9.1-87.3%; however some treatments also induced significant decreases. Increases in cone biomass production by 1.5-19.6% were also measured in response to treatment in both seasons. Induced changes in cone biomass production and terpenophenolic accumulation were most dependent on cultivar and the developmental stage at which plants were treated.;In a second series of experiments we conducted a targeted analysis of phenolic acids, flavonoids, and terpenophenolics over 22 days following a single Pro-Ca treatment conducted during early flowering. Terpenophenolics significantly increased following treatment, and coincided with changes in the flavonoid biosynthetic pathway including accumulation of metabolic precursors upstream from flavanone-3-hydroxylase, and decreases in flavonoid products downstream from flavanone-3-hydroxylase. In addition to changes in known compounds, marker analysis revealed the presence of two markers in treated samples not previously reported from hops. One of these markers has been tentatively identified as the antimicrobial compound luteoliflavan.;This research provides insight into the relationship between secondary metabolic pathways in hops and indicates targets for future research into perturbation of metabolic pathways to increase medicinal and flavor compounds in hops.
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Type
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dissertation
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Source
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2009_2013.csv
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degree
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Ph.D.
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Program
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Biology
