http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Breeding for Bioactive Compounds in Vigna Unguiculata L. (WALP.)
One of the many ways to address health, obesity and hunger issues is genetic bio-fortification, a strategy of breeding or transforming staple crops with micronutrients and vitamins. This dissertation details efforts to bio-fortify bioactive compounds (phenols, antioxidants, condensed tannins, flavonoids and anthocyanins) in Vigna unguiculata, a staple legume grain crop. Approaches included screening of genetic variation in polyphenolic compositions to identify potential varieties and phenotypes, evaluating the impact of environment (drought stress) on these compositions and elucidating the underlying genetics of their inheritance. Our screening showed significant diversity among genotypes for phenols (2.05 -15.48 mg GAE/g), condensed tannin (0.05 -15.29 mg CE/g) and antioxidant activity (4.0 -201.8 [mu]M TE/g). The highest levels of phenols and antioxidant activity were observed in genotypes with light brown, black and red seed coat color, and those with smooth texture and medium maturity (70-90 days). Red and black phenotypes showed the highest content of flavan-3-ols, flavonols and phenolic acids among all color groups, with values of 169 [mu]g CE/g, 26.17 [mu]g QHE/g, 27.14 [mu]g GAE/g for red and 281 [mu]g CE/g, 23 [mu]g QHE/g and 25 GAE/g for black phenotypes. When studying the impact of drought stress, genotype X treatment and treatment X year interactions for bioactive compounds were significant when tested under irrigated and drought stress conditions. Anthocyanins showed a 14 % decrease under drought stress. The genotypes that were stable to drought stress are favorable for breeding programs in preparation towards climate change. An FTNIR method was established for high-throughput, non-destructive quantification of bioactive compounds. This was used in inheritance studies of bioactive compounds. Phenols, condensed tannins and flavonoids showed heterosis in F1 and exhibit transgressive segregation in F₂ populations. The information presented in this manuscript will be useful for nutritional improvement of cowpeas, where potential genotypes and phenotypes with health benefits offered by enhanced contents of bioactive compounds can be improved further upon. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/149617
"Major Subject: Molecular and Environmental Plant Sciences"
Doctor of Philosophy Texas A & M University 2013 http://hdl.handle.net/1969.1/149617
Major Molecular and Environmental Plant Sciences