Pyrrolizidine Alkaloids in Crotalaria Taxa from Northern Australia: Risk to Grazing Livestock

Fletcher, Mary T.; McKenzie, R. A.; Blaney, B. J.; Reichmann, Keith G.

doi:10.1021/jf8026099

Cited by 40 publications

(58 citation statements)

References 34 publications

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“…About half of these PAs formed are toxic. Therefore, The PA-containing plants are poisonous to livestock and wildlife and have caused tremendous livestock loss (Arzt and Mount, 1999;de Lanux-Van Gorder, 2000;Fletcher et al, 2009;Fowler, 1968;Knight et al, 1984;Seaman, 1978Seaman, , 1987Sharrock, 1969;van der Watt et al, 1972;Wiltjer and Walker, 1974). PAs are also the leading plant toxins associated with disease in humans through contamination of staple foods, honey, milk, herbal teas and herbal medicines (Arseculeratne et al, 1981(Arseculeratne et al, , 1985Bach et al, 1989;Bah et al, 1994;Culvenor et al, 1981;Deinzer et al, 1977;Dickinson et al, 1976;Edgar et al, 1992Edgar et al, , 2002Huxtable et al, 1986;Jago, 1969;Kumana et al, 1983Kumana et al, : 1985Mattocks, 1980;Ridker et al, 1985;Roitman, 1981;Steenkamp et al, 2000;White et al, 1984;Zhao et al, 1989).…”

Section: Introduction Occurrence and Toxicitymentioning

confidence: 99%

Genotoxicity of pyrrolizidine alkaloids

Chen

Mei

2010

J of Applied Toxicology

181

133

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Section: Introduction Occurrence and Toxicitymentioning

confidence: 99%

Genotoxicity of pyrrolizidine alkaloids

Chen

Mei

2010

J of Applied Toxicology

181

133

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“…The negative PA adduct result on the other properties" could be interpreted as the horses not eating plants near or at the time of sampling. Concentration of PAs within Crotalaria medicaginea specimens are significant when compared to the 3.9 mk/kg of hepatotoxic PA found in an isolated specimen of the toxic Crotalaria novae-hollandia (Fletcher et al, 2009) which was growing on a roadside east of the study area. The source of PA"s was therefore, most likely a local variety of Crotalaria medicaginea because it was the only hepatotoxic plant identified during field trips to affected properties and because most affected horses grazed unsupplemented in large paddocks.…”

Section: Discussionmentioning

confidence: 84%

“…Another environmental determinant that may also have been involved was the large preceding wet season which would have increased the biomass of this plant making potentially more of it available. It is also known that PA concentration may vary with stage of plant growth, plant part and desiccation as well as temporally and spatially (Stegelmeier et al, 1999;Fletcher et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

“…The taxonomy of Australia"s Crotalaria sp. have been reviewed (Holland, 2002) and more recently samples of 24 Crotalaria taxa gathered from across northern Australia were analysed in order to determine their PA content and toxic potential, which varies with chemical structure of the alkalaoid (Fletcher et al, 2009). The environment also influences the toxic potential of PA containing plants directly by affecting plant biomass and toxin concentration, and indirectly by affecting plant intake (Stegelmeier, 1999).…”

Section: Introductionmentioning

confidence: 99%

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A field investigation into a suspected outbreak of pyrrolizidine alkaloid toxicosis in horses in western Queensland

Robinson¹,

Gummow

2015

Preventive Veterinary Medicine

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A disease outbreak investigation was conducted in western Queensland to investigate a rare suspected outbreak of pyrrolizidine alkaloid (PA) toxicosis in horses. Thirty five of 132 horses depastured on five properties on the Mitchell grass plains of western Queensland died in the first six months of 2010. Clinical-pathological findings were consistent with PA toxicosis. A local variety of Crotalaria medicaginea was the only hepatotoxic plant found growing on affected properties. Pathology reports and departure and arrival dates of two brood mares provided evidence of a pre wet season exposure period. All five affected properties experienced a very dry spring and early summer preceded by a large summer wet season. The outbreak was characterised as a point epidemic with a sudden peak of deaths in March followed by mortalities steadily declining until the end of June. The estimated morbidity (serum IGG > 50 IU/L) rate was 76%. Average crude mortality was 27% but higher in young horses (67%) and brood mares (44%). Logistic regression analysis showed that young horses and brood mares and those grazing denuded pastures in December were most strongly associated with dying whereas those fed hay and/or grain based supplements were less likely to die. This is the first detailed study of an outbreak of PA toxicosis in central western Queensland and the first to provide evidence that environmental determinants were associated with mortality, that the critical exposure period was towards the end of the dry 2 season, that supplementary feeding is protective and that denuded pastures and the horses physiological protein requirement are risk factors.

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“…However, Crotalaria produces toxic pyrrolizidine alkaloids (PAs), which are responsible for the occasional intoxication of grazing livestock (hepatic veno-occlusive disease). On the other hand, because of a nematocidal effect of PAs, Crotalaria species are also used for soil sanitation (8)(9)(10).…”

mentioning

confidence: 99%

New aspect of plant–rhizobia interaction: Alkaloid biosynthesis in Crotalaria depends on nodulation

Irmer

Podzun

Langel

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Infection of legume hosts by rhizobial bacteria results in the formation of a specialized organ, the nodule, in which atmospheric nitrogen is reduced to ammonia. Nodulation requires the reprogramming of the plant cell, allowing the microsymbiont to enter the plant tissue in a highly controlled manner. We have found that, in Crotalaria (Fabaceae), this reprogramming is associated with the biosynthesis of pyrrolizidine alkaloids (PAs). These compounds are part of the plant’s chemical defense against herbivores and cannot be regarded as being functionally involved in the symbiosis. PAs in Crotalaria are detectable only when the plants form nodules after infection with their rhizobial partner. The identification of a plant-derived sequence encoding homospermidine synthase (HSS), the first pathway-specific enzyme of PA biosynthesis, suggests that the plant and not the microbiont is the producer of PAs. Transcripts of HSS are detectable exclusively in the nodules, the tissue with the highest concentration of PAs, indicating that PA biosynthesis is restricted to the nodules and that the nodules are the source from which the alkaloids are transported to the above ground parts of the plant. The link between nodulation and the biosynthesis of nitrogen-containing alkaloids in Crotalaria highlights a further facet of the effect of symbiosis with rhizobia on the ecologically important trait of the plant’s chemical defense.

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Pyrrolizidine Alkaloids in Crotalaria Taxa from Northern Australia: Risk to Grazing Livestock

Cited by 40 publications

References 34 publications

Genotoxicity of pyrrolizidine alkaloids

Genotoxicity of pyrrolizidine alkaloids

A field investigation into a suspected outbreak of pyrrolizidine alkaloid toxicosis in horses in western Queensland

New aspect of plant–rhizobia interaction: Alkaloid biosynthesis in Crotalaria depends on nodulation

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