Development of the Potential for Cyanogenesis in Maturing Black Cherry (Prunus serotina Ehrh.) Fruits

Abstract

Biochemical changes related to cyanogenesis (hydrogen cyanide production) were monitored during maturation of black cherry (Prunus serotina Ehrh.) fruits. At weekly intervals from flowering until maturity, fruits (or selected parts thereof) were analyzed for (a) fresh and dry weights, (b) prunasin and amygdalin levels, and (c) levels of the catabolic enzymes amygdalin hydrolase, prunasin hydrolase, and mandelonitrile lyase. During phase 1 (0-28 days after flowering [DAF]), immature fruits accumulated prunasin (mean: 3 micromoles/fruit) but were acyanogenic because they lacked the above enzymes. Concomitant with cotyledon development during mid-phase 11, the seeds began accumulating both amygdalin (mean: 3 micromoles/seed) and the catabolic enzymes and were highly cyanogenic upon tissue disruption. Meanwhile, prunasin levels rapidly declined and were negligible by maturity. During phases 11(29-65 DAF) and III (66-81 DAF), the pericarp also accumulated amygdalin, whereas its prunasin content declined toward maturity. Lacking the catabolic enzymes, the pericarp remained acyanogenic throughout all developmental stages.

Utilization of Amygdalin during Seedling Development of Prunus serotina

“…The subsequent degradation of linustatin by a diglucosidase yields HCN, which is detoxified to L-Asn by P-CAS and P-cyanoalanine hydrolase. Thus, instead of being lost to the environment as HCN, the nitrogen content of linamarin is returned to the general amino acid Recently, we described the accumulation of the cyanogenic diglucoside amygdalin by developing black cherry seeds (Swain et al, 1992a). Extending these studies, our goal was to ascertain whether amygdalin is catabolized upon germination to furnish the developing seedlings with reduced nitrogen and carbonyl compounds.…”

“…A known number (usually n = 10) of stage 1 to 4 seeds or seedling parts was extracted in methanol and chromatographed by HPLC to resolve amygdalin and prunasin (Swain et al, 1992a), which were quantitated as described by Brinker and Seigler (1989).…”

“…Their cyanogenicity has caused numerous cases of acute cyanide poisoning in humans and livestock (Poulton, 1983). In previous studies, our laboratory monitored the development of the potential for cyanogenesis of maturing black cherry (Prunus serotina) fruits (Swain et al, 1992a). Levels of amygdalin, its corresponding monoglucoside (R)-prunasin, and AH, PH, and MDL were determined from soon after flowering until maturity.…”

Tissue and Subcellular Localization of Enzymes Catabolizing (R)-Amygdalin in Mature Prunus serotina Seeds

“…Prior to immunoblotting analysis, homogenates were centrifuged for 5 min in a Beckman Microfuge, and supernatants were diluted to contain equal protein concentrations as determined by the Bradford (1) procedure Proteins were subjected to SDS-PAGE on 10% gels (10), electroblotted to nitrocellulose membranes using a Bio-Rad Trans-Blot apparatus (25), and challenged with monospecific polyclonal ant bodies (12,27). Anti-AH, anti-PH, and anti-MDL antisera were diluted 1:500, 1:500, and 1:750, respectively, before use.…”

“…Anti-AH, anti-PH, and anti-MDL antisera were diluted 1:500, 1:500, and 1:750, respectively, before use. Immune complexes were visualized using horseradish peroxidase-conjugated GAR IgG (diluted 1:3000) as secondary antibody (25).…”