Abstract Detail


Masondo, Nqobile [1], Masike, Keabetswe [2], Makunga, Nokwanda [1].

Impact of salinity and nutrient stress on the metabolite profile of a commercially important South Africa medicinal plant - Sutherlandia frutescens (L.) R.Br. ex W.T.Aiton (Fabaceae).

Sutherlandia frutescens (L.) R.Br. (Fabaceae) is an indigenous southern African medicinal plant commonly known as “cancer bush”. The diverse pharmacological properties of Sutherlandia have been attributed to the presence of various compounds including free amino acids (arginine, asparagine), L-canavanine, D-pinitol, gamma (γ) aminobutyric acid (GABA), and unique triterpenoid glycosides compounds known as sutherlandins and sutherlandiosides. The medicinal properties, adaptogen and tonic uses stimulated the plants commercial value in South Africa and now also in international markets. However, chemical heterogeneity of the population expressed as a wide range of metabolites is highly regulated by changes in environmental conditions. Therefore, the study aimed to elucidate metabolite profile changes of S. frutescens in response to salt and nutrient stress. Biomarkers, sutherlandin C (725.19-m/z), D (725.19-m/z) and sutherlandioside A (653.42-m/z), B (653.45-m/z), C (651.40-m/z), D (635.41-m/z) were detected using LC-MS/MS based metabolome approach, where these signatures differentiated in vitro treated plants (NaCl, nitrogen and phosphorus) from the controls after cluster analysis. Furthermore, 51 compounds were identified based on their molecular formula and MSE fragmentation patterns as well as online databases including KNApSAck, METLIN and ChemSpider, with 19 unknown compounds, sutherlandioside and soyasaponin derivatives, kaempferol and flavanones. After applying vibrational spectroscopy to determine metabolites impacted by stress, GC-MS analysis of both sugars and sugar alcohols was conducted. As a response to 150 mM NaCl, nitrogen and phosphorus-deficiency, plants had increased fructose, glucose, and sucrose concentrations. Amino acids such as proline, cadaverine, putrescine, and GABA, associated with general stress response were elevated in plants exposed to stress. Many of these metabolites act as osmoregulators and are shunted into production of specialised-metabolites. GABA, canavanine and other amino acids are implicated in immunomodulatory properties of S. frutescens and so abiotic factors that cause changes in the species are likely to lead to altered chemical phenotypes, generating plants with unpredictable pharmacology. These findings are a step towards a deep understanding of how environmental attributes regulate metabolism in S. frutescens and monitoring of proteome may provide new insights on the molecular biological control of stress.

1 - Stellenbosch University, Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, Western Cape, 7602, South Africa
2 - Stellenbosch University, Biochemistry, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, Western Cape, 7602, South Africa

Medicinal plant.

Presentation Type: Oral Paper
Session: PHYS1, Physiology I
Location: Virtual/Virtual
Date: Tuesday, July 28th, 2020
Time: 1:45 PM
Number: PHYS1004
Abstract ID:505
Candidate for Awards:None

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