Nitrogen supply and abiotic stress influence canavanine synthesis and the productivity of in vitro regenerated Sutherlandia frutescens microshoots

• Published in: Journal of plant physiology Vol. 167; no. 17; pp. 1521 - 1524
• Main Authors: Colling, Janine, Stander, Marietjie A., Makunga, Nokwanda P.
• Format: Journal Article
• Language: English
• Published: Munich Elsevier GmbH 15.11.2010; Elsevier
• Subjects: Biological and medical sciences; Biomass; Canavanine; Canavanine - biosynthesis; Cancer bush; Drought; Fabaceae - drug effects; Fabaceae - growth & development; Fundamental and applied biological sciences. Psychology; In vitro testing; Lessertia frutescens; Metabolites; Nitrogen - pharmacology; Nitrogen stress; Physiology; Plant physiology and development; Plant Shoots - drug effects; Plant Shoots - physiology; Plants (organisms); Polyethylene Glycols - pharmacology; Regeneration - drug effects; Salinity; Sodium Chloride - pharmacology; Stress, Physiological - drug effects; Stresses; Synthesis; Tissue Culture Techniques; Tissue cultures, protoplasts; LC–MS–MS; MS; Lessertia frutescens; Salinity; Cancer bush; SE; DW; PEG; 0.5× nitrogen; 2× nitrogen; PGR; Nitrogen stress; Drought; HPLC; Productivity; Nitrogen fertilization; Plant physiology; Abiotic stress; Micropropagation; Nitrogen; Microplant
• ISSN: 0176-1617; 1618-1328
• DOI: 10.1016/j.jplph.2010.05.018

Environmental stresses can significantly alter the synthesis of both primary and secondary metabolites, resulting in medicinal plants with unpredictable biological activity. Here, in vitro shoot cultures of the medicinal plant Sutherlandia frutescens were used to study the impact of three abiotic stresses (nitrogen availability, drought and salinity), primarily on l-canavanine synthesis. This compound, a non-protein amino acid, is amongst those metabolites linked to the health benefits of Sutherlandia extracts. Nitrogen supplied to microplants positively correlated with canavanine levels, exhibited by a fourfold reduction when nitrates provided were halved. Although the biomass generated was lowered under these conditions, a higher capacity for rooting (52%) in comparison to the controls (37%) became evident. Only a small increase of the canavanine content in microplants growing on 100 mM NaCl medium was detected, indicating that salinity stress was not a major limitation on cavanine production, but that it played more of a role in vitro on plantlet morphogenesis. Similarly, PEG as a supplement had little to no effect on canavanine synthesis. We conclude that a deeper understanding of the nutritional requirements for the agricultural crop management of S. frutescens, which serves the herbal products industry, is needed.