MODULATION OF RESERVE AND ALKALOID CONTENT DURING AND AFTER GERMINATION IN Erythrina velutina
Mulungu, pioneer species, reserve mobilization, seed germination, seedling establishment
Considering the medicinal potential of Erythrina velutinaWilld., a woody species native to the Caatinga, the aim of this work was to characterize the mobilization of reserves in parallel with the content secondary metabolites during seed germination and seedling establishment. Hence, seeds were scarified, surface-sterilized, planted between towel paper sheets and cultivated under controlled conditions. Then, seedlings were transferred to distilled water in hydroponics and cultivated in a greenhouse. In a time-coarse experiment, seedling growth, reserve mobilization and the content of soluble sugars and secondary metabolites were measured in the cotyledons during and after germination. Germination included the stages of imbibed seed and radicle protrusion, whereas establishment encompassed hypocotyl emergence, plumule hook opening, and the emergence of cordiform leaves, first trifoliate leaf and second trifoliate leaf. Seeds contained 20% starch, 14,5% storage proteins, 11,6% neutral lipids and 5,7% non-reducing sugars in dry weight basis. The major reserves were synchronically and intensely mobilized from hook opening, while non-reducing sugars were utilized from hypocotyl emergence. The activity of amylases and lipases increased from cordiform leaf emergence, coinciding with the mobilization of starch and lipids, respectively. By thin layer chromatography, it was possible to verify at least three bands of terpenes and phenolic acids during the experimentand a band of saponins until hook opening. A band of flavonoids was detected from germination, whereas another appeared at cordiform leaf emergence, remaining until the end of the experiment. Only in imbibed seeds it was possible to observe the presence of four bands of alkaloids; a major band remained along the experiment and a minor band was observed at the emergence of hypocotyl and cordiform leaves.The elucidation of these processes may help in understanding the strategies used by E. velutinato colonize the environment as a Caatinga pioneer species.