A proteomic approach to guarana seed and pericarp maturation.
Paullinia cupana Kunth var. sorbilis (Mart.) Ducke, the cultivated guarana plant, is native to the Amazon and has been valued for its medicinal, stimulant and energetic properties for centuries. The seeds are the main commercial product of the plant and the source of high amounts of purine alkaloids (caffeine and theobromine) and polyphenols (flavonoids, catechins, and tannins). Proteins involved in the development and maturation of guarana fruits in its native habitat are interesting issues for proteomics. This study presents the proteomic profile of the seed and pericarp of healthy guarana in different maturation stages. Protein contents were higher in the mature seed compared to other stages due to the accumulation of storage proteins - 11S globulins. Proteins selected for identification by mass spectrometry are mostly related to stress responses and defense and this is not unexpected for fast growing and differentiating reproductive tissues.