Tentative identification of phytochelatins, their derivatives, and Cd-phytochelatin complexes in Ocimum basilicum L. roots by Paper Spray Mass Spectrometry.

An unprecedented and direct PS-MS (paper spray ionization mass spectrometry) method was proposed for the detection of native peptides, that is, glutathiones (GSHs), homoglutathiones (hGSHs), and phytochelatins (PCs), in basil (Ocimum basilicum L.) roots before and after cadmium exposure. The roots were submitted to cold maceration followed by sonication with formic acid as the extractor solvent for sample preparation. PS-MS was used to analyze such extracts in the positive mode, and the results allowed for the detection of several GSHs, hGSHs, and PCs. Some of these PCs were not distinguished in the control samples, that is, basil roots not exposed to cadmium. Other PCs were noticed in both types of roots, uncontaminated and cadmium-contaminated, but the intensities were higher in the former samples. Moreover, long-time exposure to cadmium stimulated the formation of some of these PCs and their cadmium complexes. The results, therefore, provided some crucial insights into the defense mechanism of plants against an external stress condition due to exposure to a toxic heavy metal. The present study represents a promising alternative to investigate other crucial physiological processes in plants submitted to assorted stress conditions.

Ionomic responses of hydroponic-grown basil (Ocimum basilicum L.) to cadmium long-time exposure.

The ionomic response of basil leaves, stems, and roots to Cd2+ was evaluated in seedlings grown in a hydroponic system for 15 days. Ions were quantified by the inductively coupled plasma-mass spectrometry (ICP-MS). Cd accumulated mainly in roots, while Be, Li, Ca, Mg, and Sr in leaves, and K and Mn in stems. Compared to the control group, basil seedlings treated with Cd2+ accumulated higher Ca, Cu, Mn, Sr, and Zn contents in roots, even when exposed at low levels. Pearson positive correlations between Cd and essential and nonessential elements were mostly observed in leaves and roots (P < 0.05). On the other hand, negative correlations were observed mainly in stems with all elements except Ba, Li, Sr, and Zn. Principal component analysis showed an ionomic discrimination between leaves, stems, and roots, with Cd strongly correlated to Zn, Cu, and Sr.

Interactions between As and Se upon long exposure time and effects on nutrients translocation in golden flaxseed seedlings.

Se is a beneficial nutrient for some plant species, while As is considered a toxic element, even at low concentrations. This study investigated the interaction between As and Se on golden flaxseed (Linum usitatissimum L.) seedlings to better understand the extent of Se in the mitigation of As uptake and translocation. In addition, co-exposure experiments allowed to determine how As and Se affected absorption and distribution of the essential micronutrients Fe, Zn and Mn. Seedlings were cultivated in a 10 % v v-1 Hoagland solution supplemented with AsV, SeIV, SeVI or AsV + SeIV at different concentrations. SeVI presented the highest toxicity and translocation factor. The toxicity of AsV was attenuated by SeIV, which stimulated As uptake and translocation. SeIV reduced As accumulation, establishing a tolerance mechanism. Only a high concentration of As (200 µmol L-1) led to leaf chlorosis or seedling death, independently of co-exposure with Se species. Co-exposure also altered the uptake of Fe, Zn and Mn, without affecting As translocation from roots to shoot. In general, the interaction of As with Se was beneficial for golden flaxseed seedlings, when compared to the effects of As solely.