Seasonal Variations in Hydrogen Cyanide Concentration of Three Lotus Species

Abstract

rupted by herbivores, mechanical means, or fungal attack (Poulton, 1990). Acyanogenic (HCN negative) Lo-Cyanogenic glucosides, generally considered antinutritional factus plants or plant parts may lack the cyanoglycosides, tors, are important defense molecules against predators and, in some cases, diseases. The objectives of this study were: (i) to determine the corresponding ␤-glucosidase, or both (Kakes, 1991; the seasonal variations in hydrogen cyanide (HCN) concentration of Compton and Jones, 1985). three widely grown Lotus spp. and (ii) to assess the overall cyanogenic The major role of cyanogenic glycosides in birdsfoot potential of the different plant components of a rhizomatous cultivar trefoil (BFT) is as a feeding inhibitor. In laboratory of broadleaf birdsfoot trefoil [Lotus corniculatus L.] (BFT). In this studies, several species of insects and mollusks preferred study, we used BFT cultivars Norcen and ARS-2620, narrowleaf trefoil acyanogenic birdsfoot trefoil leaves or petals to the cy-(L. glaber Mill.) germplasm ARS-1207, and big trefoil (L. uliginosus anogenic alternatives (Compton and Jones, 1985). As Schkur.) germplasm ARS-1221. The experiments were conducted in reviewed by Compton and Jones (1985), there is evithe field and greenhouse using a randomized complete block design. dence that, in natural populations, acyanogenic plants Significant seasonal variations in HCN concentrations in Norcen, suffer disproportionate levels of herbivory. Similar re-ARS-2620, and ARS-1207 were observed. Hydrogen cyanide concentrations were greatest in spring and summer and least in winter. ARS-sults have been reported for white clover (Trifolium 1221 was acyanogenic. Of the three cyanogenic entries grown in the repens L.) based on field and laboratory experiments field study, ARS-1207 had the greatest concentration of HCN, averag- (Hughes, 1991;Ellsbury et al., 1992). Furthermore, cyaing 900 g g Ϫ1 dry matter while Norcen and ARS-2620 had similar nogenesis has long been considered a resistance factor levels of HCN. In the greenhouse, Norcen and ARS-1207 had greater against fungi. Sorghum [Sorghum bicolor (L.) Moench] HCN concentrations than ARS-2620. Partitioning of the rhizomatous root exudates containing 0.6 to 2.7 mg kg Ϫ1 CN inhibited BFT cultivar ARS-2620 demonstrated that leaves and flowers prochlamydospore germination of two Fusarium spp. (Hillduced the greatest concentration of HCN, five times as much as stems ocks et al., 1997). Yet, the presence of large amounts and ripe-seed pods. Rhizomes, which are typically produced in winter of cyanogenic compounds can inhibit active defense reand fall, did not exhibit HCN production. Seeds of Norcen and ARSactions in plants (Lieberei et al., 1989). Another possible 2620 were acyanogenic, but ARS-1207 seeds were weakly cyanogenic. However, as seeds germinated and seedlings formed cotyledons, Nor-use of cyanogenic glycosides in plants is as a storage cen, ARS-2620, and ARS-1207 exhibited HCN. Roots of all species form of reduced N (Poulton, 1990; Selmar et al., 1...

Biosynthesis of the Nitrile Glucosides Rhodiocyanoside A and D and the Cyanogenic Glucosides Lotaustralin and Linamarin in Lotus japonicus

“…as shown in Figure 9, very low levels of lotaustralin were detectable in roots of L. japonicus by LC-MS-SIM analysis, which is much more sensitive than measurements of cyanide potential. High amounts of cyanogenic glucosides in actively growing tissues and absence or presence of only minute amounts of cyanogenic glucosides in roots and seeds has earlier been reported in other Lotus species (Gebrehiwot and Beuselinck, 2001) as well as in sorghum and barley (Erb et al, 1981;Halkier et al, 1988;Halkier and Møller, 1989;Forslund and Jonsson, 1997).…”

“…Most Lotus species are cyanogenic (Gebrehiwot and Beuselinck, 2001). This is thought to reflect the presence of the two cyanogenic glucosides linamarin and lotaustralin that have been shown to be present in Lotus tenuis and Lotus arabicus (Abrol and Conn, 1966;Jones, 1977).…”

Plant chemistry and insect sequestration

“…Furthermore substantial amounts of linamarin and lotaustralin were detectable in the eggs (Nahrstedt, personal communication). Levels of CNGs can vary tremendously in plants, because cyanogenesis is a polymorphic trait, for example, in Lotus corniculatus (Fabaceae) (Gebrehiwot and Beuselinck 2001). In general, Z. filipendula larvae maintain specific ratios of CNGs and have the ability to biosynthesise them de novo in order to compensate for lower levels in Lotus plants.…”

Kinetics of the Natural Evolution of Hydrogen Cyanide in Plants in Neotropical Pteridium arachnoideum and its Ecological Significance

“…For example, cyanogenic species such as Trifolium repens contain enough cyanogenic glycosides to give between 3.2 and 350 µg of HCN g −1 dw, while others like Linum usitatisimum and Dimorphoteca ecklonis are capable of yielding a total of 910 and 1580 µg of HCN, respectively (Butler, 1965). The seasonal variability in cyanogenic glycoside content has also been recognized (Cooper-Driver et al, 1977;Gleadow and Woodrow, 2000;Gebrehiwot and Beuselinck, 2001). However, the amount of cyanogenic glycosides alone and their static potential to yield HCN have not satisfied all questions open to cyanogenesis as an effective defense strategy (Hruska, 1988;Gleadow and Woodrow, 2002).…”