Cyanogenic glycoside content of Manihot esculenta subsp. flabellifolia in south-central Rondônia, Brazil, in the center of domestication of M. esculenta subsp. esculenta

Abstract

Manioc (Manihot esculenta Crantz subsp. esculenta) is a tropical staple crop that was domesticated from M. esculenta Crantz subsp. flabellifolia in southwestern Amazonia. After domestication, different selective pressures created two large groups of varieties based on cyanogenic glycoside (HCN) content: sweet and bitter manioc. The characterization of HCN content in subsp. flabellifolia will help understand the original selection pressures that either reduced or increased the concentration of HCN in the edible root. We collected leaves, fruits and roots of five mature plants of subsp. flabellifolia chosen at random from each of six populations located in central Rondonia, Brazil. Analyses of HCN were performed by the enzymatic method with some modifications. All parts of the plant contained moderate to high (84–717 mg HCN kg−1 fresh weight) concentrations of HCN, especially in the fruits. Both the bark and the starchy flesh of roots had moderate to high concentrations of HCN (198 ± 103 and 244 ± 105 mg HCN kg−1 fresh weight, respectively), which classifies these populations as bitter.