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A high performance liquid chromatographic study of post-stress isoflavonoid accumulation in Phaseolus Vulgaris and Pisum sativum

University of British Columbia

It has been observed in some plants that their post-infectional response to a potential pathogen leads to the synthesis and accumulation of compounds which may be significant in the processes of disease resistance. Consequently, a high performance liquid chromatographic procedure has been developed which will separate complex mixtures of Phaseolus vulgaris (green bean) and Pi sum sativum (garden pea) iso-flavonoids to give a chromatographic fingerprint of the post-stress metabolic response of these plants. This system has been used to determine the time course of the accumulation of the major de novo fungitoxic metabolites (phytoalexins) of abiotically stressed plants. These accumulation rate studies represent one of the most significant applications of the HPLC procedure because the quantification of a selected number of components of a mixture by other chromatographic methods can be, at best, tedious. The HPLC procedure has also been applied to the characterization of a number of other post-stress metabolites from P_. sativum. This study led to the identification of a previously unreported 2'-methoxychalcone (4,4'-dihydroxy-2'-methoxychalcone) and its benzylstyrene analogue (4-hydroxy-(4'-hydroxy-2'-methoxybenzyl)styrene) as well as a number of compounds which have been observed from other plant sources. The characterization of benzylstyrenes from P. sativum is particularly interesting because until now these compounds have only been described from heartwoods. Consequently, their identification as de novo metabolites will allow an in vivo investigation into their biosynthesis and potential role in disease resistance. To facilitate further studies on the chemistry and biochemistry of these compounds their MS, NMR and UV properties, as they pertain to the identification of structure, have been determined. A final aspect of this study was the qualitative evaluation of the response of P. sativum to a pathogenic and a non-pathogenic fungus. These results illustrated that the plant's net response to the two fungi was similar. However, a more important aspect of the study was its demonstration that the HPLC procedure could be used to determine the effects of in vivo fungal metabolism on the plant's accumulation of isoflavonoids.

Text

2010-03-11

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http://hdl.handle.net/2429/21780

Chemistry

University of British Columbia

Graduate