Poster: Plant Interaction with Other Organisms

Abs # 913: Study of glucosinolates from Mashua (Tropaeolum tuberosum).

Presenter:	Guimaraes, Rejane L., rlg167@psu.edu
Authors	Guimaraes, Rejane L. (A)   Momotani, Ko  (B)   Flores, Hector E. (A)
Affiliations:	(A): Intercollege Program in Plant Physiology, The Pennsylvania State University (B): Department of Biology, The Pennsylvania State University

Glucosinolates are a group of amino acid-derived, sulphur-containing secondary metabolites, associated with defense mechanisms. Glucosinolates have been studied in detail in the Brassicaceae family but are also found in other plant families such as Caricaceae and Tropaeolaceae. In the latter family, mashua (Tropaeolum tuberosum), a tuber crop from the Andean highlands of Peru, has been reported to contain glucosinolates at high levels. Our goal was to characterize the glucosinolates of mashua and to investigate possible correlation with insect resistance. Quantitative analysis of total glucosinolates was determined by a glucosidase- based assay while qualitative analysis of glucosinolates was done by HPLC and mass spectrometry (MS). Comparison of the total glucosinolate content among different mashua morphotypes and different plant species showed that mashua contains moderate amounts of this compound, ranging from 1.1 to 5.7 microMoles/g of leaf tissue. Higher levels were observed in the leaves, although glucosinolates were detected in stems, tubers and roots. No significant amounts of alkenyl glucosinolates were found in leaves of mashua after MS analysis. The prevalent glucosinolates of mashua were observed to contain aromatic and indolyl groups. To investigate whether mashua glucosinolates play a role in insect- plant interactions, tests were done with aphids (Rhopalosiphum padi). Preliminary results showed a direct correlation between the glucosinolates and aphid resistance.