Almost all nectars are as clear as pure water. Colored nectar is rare among plants and is observed only a few genera including a subset of Jaltomata species (Solanaceae) that grow in Bolivia and Peru. A few species of the genus Jaltomata including J. calliantha and J. quipuscoae produce orange to red colored nectar. The function of the red nectar is debatable and was thought to be a cue for a visual attraction of the pollinators. The chemical make-up of the red nectar is currently unknown. In this study, we employed spectroscopy and liquid chromatography coupled with diode array and mass spectrometry detection techniques to elucidate the chemical structure of the red pigment from the red nectar. We observed that the color of the nectar depended on the pH and a bathochromic shift towards deep red color is observed at a neutral to a weakly basic solution. Two similar compounds with characteristic absorbance maxima of 378 nm and 402 nm were observed in reversed phase separation. A preliminary study using electrospray ionization tandem mass spectrometry revealed two dominant peaks of m/z 328.1 and 677.2 Da in positive ion mode. We are further decoupling the structure using negative ion electrospray ionization and various NMR techniques.

Chemical profiling of rare South American red nectar

255th National Meeting (2018)

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