Seasonal Variations in Hydrogen Cyanide Concentration of Three Lotus Species
- Lulseged Gebrehiwota and
- Paul R. Beuselinck *b
Cyanogenic glucosides, generally considered antinutritional factors, are important defense molecules against predators and, in some cases, diseases. The objectives of this study were: (i) to determine the seasonal variations in hydrogen cyanide (HCN) concentration of three widely grown Lotus spp. and (ii) to assess the overall cyanogenic potential of the different plant components of a rhizomatous cultivar of broadleaf birdsfoot trefoil [Lotus corniculatus L.] (BFT). In this study, we used BFT cultivars Norcen and ARS-2620, narrowleaf trefoil (L. glaber Mill.) germplasm ARS-1207, and big trefoil (L. uliginosus Schkur.) germplasm ARS-1221. The experiments were conducted in the field and greenhouse using a randomized complete block design. Significant seasonal variations in HCN concentrations in Norcen, ARS-2620, and ARS-1207 were observed. Hydrogen cyanide concentrations were greatest in spring and summer and least in winter. ARS-1221 was acyanogenic. Of the three cyanogenic entries grown in the field study, ARS-1207 had the greatest concentration of HCN, averaging 900 μg g−1 dry matter while Norcen and ARS-2620 had similar levels of HCN. In the greenhouse, Norcen and ARS-1207 had greater HCN concentrations than ARS-2620. Partitioning of the rhizomatous BFT cultivar ARS-2620 demonstrated that leaves and flowers produced the greatest concentration of HCN, five times as much as stems and ripe-seed pods. Rhizomes, which are typically produced in winter and fall, did not exhibit HCN production. Seeds of Norcen and ARS-2620 were acyanogenic, but ARS-1207 seeds were weakly cyanogenic. However, as seeds germinated and seedlings formed cotyledons, Norcen, ARS-2620, and ARS-1207 exhibited HCN. Roots of all species were acyanogenic.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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