Cyanogenic Glycoside Levels in Saskatoon Serviceberry Item Type text; Article Authors Majak, W.; Quinton, D. A.; Broersma, K. Citation Majak, W., Quinton, D. A., & Broersma, K. (1980). Cyanogenic glycoside levels in Saskatoon serviceberry. Journal of Range Management, 33(3), 197-199. DOI 10.2307/3898283 Publisher Society for Range Management Journal Journal of Range Management Rights Copyright © Society for Range Management. Download date 01/10/2021 15:02:39 Item License http://rightsstatements.org/vocab/InC/1.0/ Version Final published version Link to Item http://hdl.handle.net/10150/646314 Cyanogenic Glycoside Levels in Saskatoon Serviceberry w. MAJAK, D.A. QUINTON, AND K. BKOEKSMA Abstract The concentration of prunasin, the cyanogenic glycoside in Sas- shrub collected from various locations and over a 12 month katoon serviceberry, was determined in leaves and twigs over a 12- period. The results will point to some of the risk factors month period. Eight shrubs were monitored, three of which were involved when serviceberry is browsed by ruminants. located in the ponderosa pine zone and the remainder in the Materials and Methods Douglasfir zone. Qualitative tests indicated that the cyanide poten- tial of serviceberry persisted continuously at all the experimental Sample Collection sites in both leaves and twigs. Quantitative analyses showed that Serviceberry samples were collected at eight sites along a 30-km prunasin levels in twigs were substantially higher in current year’s stretch on the west side of the North Thompson River Valley growth as compared to previous year’s growth. The highest pru- between Kamloops (elev. 339 m) and McLure (elev. 373 m), B.C. nasin levels were obtained in new growth of leaves and twigs The sites were numbered in sequence from 1 to 8 beginning with the following initiation and and this potentially hazardous period for most northerly site at McLure. At each site during September 1977 browsers is described. Shrubs yielded lower prunasin levels when to August 1978, the same shrub was sampled at 4 to 6-week they were associated with ground water indicator species. intervals. At least five terminal ends of branches containing current and previous year’s growth were snipped from each shrub and Saskatoon serviceberry (Amelanchier alnifolia Nutt.) transported in plastic bags on dry ice. In a coldroom, the leaves (Hitchcock and Cronquist 1976) has long been recognized were separated from the twigs, and these were snipped at the bud as an important if not preferred browse for rangeland live- scars into current and previous year’s growth. Composite shrub stock and wildlife (Plummer et al. 1968). The proportion of samples (approximately 10 g fresh weight) representing each part serviceberry in the diet of free-ranging mule deer (Odocoi- from each site were stored in plastic bags at -20’. leus hemionus hemionus) for example, varies from low to Prunasin Determination moderate (Willms et al. 1976; Kufeld et al. 1973), and in the Frozen shrub samples were chilled on dry ice for an hour and British Columbia Interior, where the shrub is distributed then ground in powdered dry ice using a 20-mesh screen in an widely, field observations indicate heavy utilization by Intermediate Wiley mill. Excess dry ice in the sample was allowed range cattle’. Although the toxicity of chokecherry (Prunus to dissipate at -20” over a period of 24 to 48 hours. To prevent Virginiana) is well known (Garner 1967; Radeleff 1970), losses of HCN through the action of endogenous enzymes it was only recently was the closely related serviceberry implicated essential to maintain the freshly ground sample in a frozen state as a poisonous plant (Majak et al. 1978). We identified the and to load the incubation flasks as quickly as possible. Therefore toxic principle in serviceberry as the cyanogenic glycoside the ground sample was transported on dry ice to a coldroom (4O C) prunasin (Majak et al. 1978) and subsequently confirmed where a subsample (100 mg) was introduced into the main that the cyanogenic properties of chokeberry were attributa- compartment of a 25-ml Erlenmeyer flask containing a centre well ble to the same compound2. (Secor et al. 1976). Phosphate buffer (0.1 M, pH 6.4), 2 ml, and p- glucosidase (almond emulsin) solution (0.1% in O.lM phosphate One half g of prunasin can produce 46 mg of hydrogen buffer, pH 6.4), 1.0 ml, were added immediately to the main cyanide (HCN), and for grazing animals daily doses in compartment, 0.4 ml. N NaOH was added to the centre well and excess of 50 mg HCN/ kg body weight are considered to be the flask was sealed and incubated at 35°C for 16 hours. At that dangerous (Radeleff 1970). Through the action of endogen- time the NaOH from the centre well was removed, adjusted to a ous enzymes, the HCN can be liberated in either the plant or volume of 1 ml and duplicate aliquots were analyzed for cyanide by the animal. In plants this can occur as a result of cellular the calorimetric procedure of Aldridge (1944). Since there was injury (frost) in which degradative enzymes are brought into close agreement between replicate incubations (<III 5% variation contact with glycosides which appear to be isolated in with respect to duplicate cyanide determinations), a single vacuoles (Saunders and Conn 1978). In animals this occurs incubation of each sample was considered sufficient. through the catalytic action of ingested plant tissue enzymes Commercially available amygdalin standards ((R)-mandelonitrile- /I-D-glucosido-6-D-P-glucoside) were incubated concomitantly and rumen microbial enzymes (James et. al. 1975; Conn and standard curves were derived for HCN enzymatically released 1978). from amygdalin. Prunasin ((R)-mandelonitrile-P_D-glucoside) The present study was designed to reveal the cyanide concentrations were calculated from the HCN determinations by potential of serviceberry. To achieve this goal, prunasin multiplying by the molecular weight ratio, 295/27. Subsamples of concentrations were monitored in different parts of the the frozen, ground material were used for duplicate dry weight determinations which varied by <f 2%. Authors are plant biochemist, range ecologist, and agronomist, Research Station, Agriculture Canada, Kamloops, British Columbia. This report is contribution No. 282. Statistical Analysis The technical assistance of Ruth McDiarmid and Lynne Clark is gratefully acknowledged. The prunasin values were examined in two groups representing Contribution No. 282. the Fall to Winter interval (September 1977 to April 1978) and the Manuscript received December 18, 1978. Spring to Summer interval (May 1978 to August 1978). Analysis IQuinton, D.A. 1978. unpublished results. of variance was conducted for each group with prunasin concen- *Majak, W. 1978. unpublished results. tration (percent dry weight) as the dependent variable and site (A), JOURNAL OF RANGE MANAGEMENT 33(3), May 1980 197 shrub part (B) and collection date (C) as the three factors. During branches may point to a relationship between chemical and the Fall-Winter interval shrub parts consisted of twig segments spatial factors, and whether cyanogenic glycoside gradients representing current and previous year’s growth. Spring-Summer occur within a shrub remains to be seen. shrub parts included leaves, and twig segments representing new A shrub containing 1.5% prunasin has a cyanide potential and previous year’s growth. Two observations per cell were derived from duplicate prunasin determinations and the underestimate of of 0.14 g HCN/ 100 g dry matter. Daily doses of HCN in variation per cell was reduced by using the ABC interaction mean excess of 10 g would be considered dangerous for a grazing square term as the denomintor in calculating Fvalues. The Fall- animal weighing 200 kg (Radeleff 1970). If the daily Winter experiment consisted of 112 cells representing eight sites, consumption rate of the 200 kg animal is 2.5% of its body seven collection dates, and two shrub parts. The Spring-Summer weight or 5 kg dry matter, the animal could possibly absorb experiment consisted of 96 cells representing eight sites, four col- 7.0 g HCN from the shrub or just under the dangerous daily lection dates, and three shrub parts. Levels of significant variables dose. Prunasin levels in excess of 1.5%, therefore, could be were compared using Duncan’s new multiple range test (P = .05). considered hazardous. However, if the animal is unable to Results and Discussion efficiently detoxify the absorbed HCN, the lethal dose is substantially lowered. Previously we reported that mature Cyanogenesis in Serviceberry mule deer expired after consuming serviceberry twigs at the In order to examine a cross-section of serviceberry rate of 1 kg fresh wt/day for a week (Majak et al. 1978). shrubs, the experimental sites were selected in a transect that Although the consumption rate was relatively low, (The provided a moisture gradient and a transition in vegetation potential cyanide dose was estimated as 11 mg HCN/ kg/ zones. The moisture differences were reflected in both sea- day) a reduced detoxification rate may have contributed to sonal and annual rainfall records. Seasonal (May to Sep- their demise. tember) records indicated that during this period the average rainfall for McLure was 40% higher than for Kam- Variation in Prunasin Concentration 100~s~. Similarly, the average annual precipitation for Bar- Concentrations of prunasin differed between sites, shrub riere, B.C.,situated 17 km north of McLure, was 44 cm or parts, and collection dates; and there were a number of 76% greater than the yearly average for Kamloops (Environ- significant interactions of these factors (Table 1). ment Canada 1975). Within this moisture gradient a vegeta- tion transition occurred with the drier sites (6, 7, and 8 Table 1. Analysis Of variance for the concentration of prunasin in serviceberry. situated in the ponderosa pine (Pinusponderosa) zone, and the remainder in the Douglasfir (Pseudotsuga menziesii) Experiment Source df F zone.