Chemical, genetic, and ethnobotanical diversity in Asian eggplant
Item
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Title
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Chemical, genetic, and ethnobotanical diversity in Asian eggplant
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Identifier
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d_2009_2013:18d367c3988a:11513
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identifier
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12004
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Creator
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Meyer, Rachel Sarah,
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Contributor
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Amy Litt
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Date
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2012
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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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Botany | Plant sciences | Biochemistry | Genetics | domestication | eggplant | ethnobotany | genetic regulation | phenolics | Solanaceae
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Abstract
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Eggplants (Solanum melongena L.) were domesticated in tropical Asia where they are used abundantly as both food and medicine. Human selection has produced hundreds of landraces that differ in morphology and chemistry in ways that may be related to local ethnobotanical preferences. Here I present a study of the genetic, phytochemical, and ethnobotanical diversity of Asian eggplant landraces and wild relatives, which together aimed to identify the molecular and chemical differences among lineages, correlate these differences with domestication and possible selection pressures, and generate hypotheses about shifts in gene regulation that could have caused these differences. Phylogeographic analyses revealed that eggplants were domesticated at least three times, in India, southern China, and the Indo-Malayan islands (Malesia). Interviews and literature review of contemporary and historic ethnobotanical data on eggplant from India, China, and Malesia, revealed largely different medicinal uses of eggplant among these regions, suggesting separate domestications could have produced fruit with different phytochemistry. Analyses of eggplant chemical profiles spanning 43 phenolic compounds, many of which have therapeutic and flavorful qualities, were compared to genetic and geographic data. Results showed that these putatively independently domesticated lineages have significantly different levels of hydroxycinnamic acid polyamine amides, which actually may contribute to fruit texture and size, in addition to health beneficial qualities of the fruit. Analyses also revealed all three domestication events produced eggplants with lower total phenolic abundance, suggesting milder flavor was preferred that lowered health beneficial compounds. Study of genes expression levels of 13 enzymes in the phenolic pathway revealed that differential expression of six genes may underlie the different phytochemical profiles; these genes encode spermine and spermidine hydroxycinnamoyl transferases, hydroxycinnamoyl transferase, and cinnamoyl 3-hydrolase. These studies allowed me to propose detailed routes of phenolic biosynthesis in eggplant, and suggest that expression levels of these potential key regulatory genes of hydroxycinnamic acid synthesis were altered during the domestication process in multiple centers of domestication.
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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
