Tissue Level Compartmentation of (R)-Amygdalin and Amygdalin Hydrolase Prevents Large-Scale Cyanogenesis in Undamaged Prunus Seeds

Poulton, Jonathan E.; Li, Chun Ping

doi:10.1104/pp.104.1.29

Cited by 69 publications

(47 citation statements)

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“…However, our immunocytochemical localization studies might argue against the partial hydrolysis of amygdalin. As shown by previous studies with mature seeds, amygdalin is restricted to the ground parenchymal cells of the cotyledons, whereas AH and PH are procambial enzymes (Poulton and Li, 1994). Because the current immunolocalization studies failed to detect AH (or PH) within the ground parenchyma at any time during stages 1 to 4, it seems probable that amygdalin must pass upon germination to the procambium for catabolism.…”

Section: Discussionmentioning

confidence: 54%

“…Levels of amygdalin, its corresponding monoglucoside (R)-prunasin, and AH, PH, and MDL were determined from soon after flowering until maturity. At maturity, each seed contained approximately 3 pmol of amygdalin, which is located within the cotyledonary parenchyma cells (Poulton and Li, 1994). By contrast, AH and PH are restricted to the procambium (Swain et al, 1992b).…”

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Utilization of Amygdalin during Seedling Development of Prunus serotina

Swain

Poulton

1994

Plant Physiol.

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Cotyledons of mature black cherry (Prunus serotina Ehrh.) seeds contain the cyanogenic diglucoside @)-amygdalin. The levels of amygdalin, its corresponding monoglucoside (R)-prunasin, and the enzymes that metabolize these cyanoglycosides were measured during the course of seedling development. During the first 3 weeks following imbibition, cotyledonary amygdalin levels declined by more than 80%, but free hydrogen cyanide was not released to the atmosphere. Concomitantly, prunasin, which was not present in mature, ungerminated seeds, accumulated in the seedling epicotyls, hypocotyls, and cotyledons to levels approaching 4 pmol per seedling. Whether this prunasin resulted from amygdalin hydrolysis remains unclear, however, because these organs also possess UDPChandelonitrile glucosyltransferase, which catalyzes de novo prunasin biosynthesis. The reduction in amygdalin levels was paralleled by declines in the levels of amygdalin hydrolase (AH), prunasin hydrolase (PH), mandelonitrile lyase (MDL), and j3-cyanoalanine synthase. At all stages of seedling development, AH and PH were localized by immunocytochemistry within the vascular tissues. In contrast, MDL occurred mostly in the cotyledonary parenchyma cells but was also present in the vascular tissues. Soon after imbibition, AH, PH, and MDL were found within protein bodies but were later detected in vacuoles derived from these organelles.

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Section: Discussionmentioning

confidence: 54%

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confidence: 99%

Utilization of Amygdalin during Seedling Development of Prunus serotina

Swain

Poulton

1994

Plant Physiol.

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“…In case of injury, the b-glucosidase is brought into contact with its substrate. By hydrolysis of the cyanogenic glycosides, a-hydroxynitriles are formed that are relatively unstable and dissociate either spontaneously or are enzymatically accelerated by an a-hydroxynitrile lyase into HCN and an aldehyde or a ketone (Conn, 1980;Hösel and Conn, 1982;Poulton, 1990;Poulton and Li, 1994;Swain et al, 1992). Hydrogen cyanide is toxic because of its affinity to the terminal cytochrome oxidase in the mitochondrial respiratory pathway and a number of other reactions (Solomonson, 1981;Brattsten et al, 1983).…”

Section: Introductionmentioning

confidence: 99%

Plant Cyanogenesis of Phaseolus lunatus and its Relevance for Herbivore–Plant Interaction: The Importance of Quantitative Data

2005

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Abstract-Quantitative experimental results on the antiherbivorous effect of cyanogenesis are rare. In our analyses, we distinguished between the total amount of cyanide-containing compounds stored in a given tissue [cyanogenic potential (HCNp)] and the capacity for release of HCN per unit time (HCNc) from these cyanogenic precursors as a reaction to herbivory. We analyzed the impact of these cyanogenic features on herbivorous insects using different accessions of lima beans (Phaseolus lunatus L.) with different cyanogenic characteristics in their leaves and fourth instars of the generalist herbivore Schistocerca gregaria Forskål (Orthoptera, Acrididae). Young leaves exhibit a higher HCNp and HCNc than mature leaves. This ontogenetic variability of cyanogenesis was valid for all accessions studied. In no-choice bioassays, feeding of S. gregaria was reduced on high cyanogenic lima beans compared with low cyanogenic beans. A HCNp of about 15 mmol cyanide/g leaf (fresh weight) with a corresponding HCNc of about 1 mmol HCN released from leaf material within the first 10 min after complete tissue disintegration appears to be a threshold at which the first repellent effects on S. gregaria were observed. The repellent effect of cyanogenesis increased above these thresholds of HCNp and HCNc. No repellent action of cyanogenesis was observed on plants with lower HCNp and HCNc. These low cyanogenic accessions of P. lunatus were consumed extensivelyVwith dramatic consequences for the herbivore. After consumption, locusts showed severe symptoms of intoxication. Choice assays confirmed the feeding preference of locusts for low over high cyanogenic leaf material of P. lunatus. The bioassays revealed total 0098-0331/05/0700-1445/0 # 2005 Springer Science + Business Media, Inc. 1445Journal of Chemical Ecology, Vol. 31, No. 7, July 2005 DOI: 10.1007/s10886-005-5791-2 * To whom correspondence should be addressed. E-mail: dballhorn@iangbot.uni-hamburg.de losses of HCN between 90 and 99% related to the estimated amount of ingested cyanide-containing compounds by the locusts. This general finding was independent of the cyanogenic status (high or low) of the leaf material.

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“…2; Sánchez-Pérez et al, 2008). In the cotyledons of black cherry seeds, PHs have previously been shown to be localized in the vacuoles of the phloem parenchyma cells (Poulton and Li, 1994). In a recent study carried out using sweet and bitter almond cultivars, it was reported that the UDPGglucosyltransferase UGT85A19 catalyzing the conversion of mandelonitrile into prunasin showed a 3-fold higher activity in bitter compared with sweet cultivars and with the main activity localized in the tegument .…”

Section: Discussionmentioning

confidence: 99%

“…Notably, the amygdalin-forming glucosyltransferase activity was at the same level in the sweet and bitter cultivars studied. Amygdalin accumulation is also observed in other Rosaceae seeds, such as in apples (Malus domestica), apricots (Prunus armenaica), black cherries (Prunus serotina), peaches (Prunus persica), and plums (Prunus domestica; McCarty et al, 1952;Conn, 1980;Frehner et al, 1990;Møller and Seigler, 1991;Swain et al, 1992;Poulton and Li, 1994).…”

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Prunasin Hydrolases during Fruit Development in Sweet and Bitter Almonds

Sánchez‐Pérez

Belmonte²,

Borch

et al. 2012

Plant Physiology

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Amygdalin is a cyanogenic diglucoside and constitutes the bitter component in bitter almond (Prunus dulcis). Amygdalin concentration increases in the course of fruit formation. The monoglucoside prunasin is the precursor of amygdalin. Prunasin may be degraded to hydrogen cyanide, glucose, and benzaldehyde by the action of the b-glucosidase prunasin hydrolase (PH) and mandelonitirile lyase or be glucosylated to form amygdalin. The tissue and cellular localization of PHs was determined during fruit development in two sweet and two bitter almond cultivars using a specific antibody toward PHs. Confocal studies on sections of tegument, nucellus, endosperm, and embryo showed that the localization of the PH proteins is dependent on the stage of fruit development, shifting between apoplast and symplast in opposite patterns in sweet and bitter cultivars. Two different PH genes, Ph691 and Ph692, have been identified in a sweet and a bitter almond cultivar. Both cDNAs are 86% identical on the nucleotide level, and their encoded proteins are 79% identical to each other. In addition, Ph691 and Ph692 display 92% and 86% nucleotide identity to Ph1 from black cherry (Prunus serotina). Both proteins were predicted to contain an amino-terminal signal peptide, with the size of 26 amino acid residues for PH691 and 22 residues for PH692. The PH activity and the localization of the respective proteins in vivo differ between cultivars. This implies that there might be different concentrations of prunasin available in the seed for amygdalin synthesis and that these differences may determine whether the mature almond develops into bitter or sweet.

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Tissue Level Compartmentation of (R)-Amygdalin and Amygdalin Hydrolase Prevents Large-Scale Cyanogenesis in Undamaged Prunus Seeds

Cited by 69 publications

References 20 publications

Utilization of Amygdalin during Seedling Development of Prunus serotina

Utilization of Amygdalin during Seedling Development of Prunus serotina

Plant Cyanogenesis of Phaseolus lunatus and its Relevance for Herbivore–Plant Interaction: The Importance of Quantitative Data

Prunasin Hydrolases during Fruit Development in Sweet and Bitter Almonds

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