Alternative Strategies in Response to Saline Stress in Two Varieties of Portulaca oleracea (Purslane).

Purslane (Portulaca oleracea) is a globally-distributed plant with a long history of use in folk medicine and cooking. We have developed purslane as a model system for exploring plant responses to stress. We exposed two varieties of purslane to saline stress with the objective of identifying differences between the varieties in the plasticity of morphological and physiological traits. The varieties responded to saline stress with significantly different changes in the measured traits, which included inter alia biomass, flower counts, proline concentrations and betalain pigment concentrations. The alternative responses of the two varieties consisted of complex, simultaneous changes in multiple traits. In particular, we observed that while both varieties increased production of betalain pigments and proline under saline stress, one variety invested more in betalain pigments while the other invested more in proline. Proline and betalain pigments undoubtedly play multiple roles in plant tissues, but in this case their role as antioxidants deployed to ameliorate saline stress appears to be important. Taken holistically, our results suggest that the two varieties employ different strategies in allocating resources to cope with saline stress. This conclusion establishes purslane as a suitable model system for the study of saline stress and the molecular basis for differential responses.

Toxic plants: a chemist's perspective.

Chemistry has long been an integral part of toxicology, as the two fields originated in much the same way: the investigation of plants with interesting properties. In this chapter I review the role that chemistry has played in understanding toxic and medicinal plants. After some introductory remarks, three broad areas are addressed: the role of natural products in understanding plant taxonomy and evolution, recent developments in chemical synthesis, especially efforts to discover and efficiently synthesize novel structures based upon naturally occurring toxins, and finally, developments in the new field of systems toxicology, which seeks to integrate all aspects of an organism's response to toxic insult.

Application of 31P NMR spectroscopy and chemical derivatization for metabolite profiling of lipophilic compounds in human serum.

New methods for obtaining metabolic fingerprints of biological samples with improved resolution and sensitivity are highly sought for early disease detection, studies of human health and pathophysiology, and for better understanding systems biology. Considering the complexity of biological samples, interest in biochemical class selection through the use of chemoselective probes for improved resolution and quantitation is increasing. Considering the role of lipids in the pathogenesis of a number of diseases, in this study fingerprinting of lipid metabolites was achieved by (31)P labeling using the derivatizing agent 2-chloro-4,4,5,5-tetramethyldioxaphospholane. Lipids containing hydroxyl, aldehyde and carboxyl groups were selectively tagged with (31)P and then detected with good resolution using (31)P NMR by exploiting the 100% natural abundance and wide chemical shift range of (31)P. After standardizing the reaction conditions using representative compounds, the derivatization approach was used to profile lipids in human serum. The results show that the (31)P derivatization approach is simple, reproducible and highly quantitative, and has the potential to profile a number of important lipids in complex biological samples.