Animal physiology and genetic aspects of ryegrass staggers in grazing sheep.
Ryegrass staggers (RGS) is a metabolic disease of herbivores, caused by the ingestion of perennial ryegrass (Lolium perenne L.) containing a fungal endophyte (Neotyphodium lolii) which produces a tremorgenic toxin, lolitrem B. RGS has a major economic impact for agriculture in New Zealand as well as internationally. Management of RGS in grazing sheep can be problematic, and there is an incomplete knowledge of the interaction between the toxin and the grazing animal. This review is focused on recent advances in understanding the molecular physiology of RGS in the affected animal as well as the influence of animal genetics on the degree of susceptibility to RGS. Investigations to date suggest that the primary target for toxin is the large conductance, calcium-activated, potassium (BK) channel, resulting in disruption of neuromuscular junction signalling. Genetic investigation has established the existence of genes influencing resistance to RGS, however their identity has not been confirmed and their impact has not been established. Studies to date suggest that a multi-gene selection approach will be necessary in order to develop an effective selection tool for use in the agricultural industries.
a Deceased. Formerly of Animal Genetics , AgResearch, Ruakura Research Centre , Private Bag 3123, Hamilton , New Zealand.
C A
CA
Morris
b Cawthron Institute , Private Bag 2, Nelson 7010 , New Zealand.
T T
TT
Wheeler
c Bioinformatics and Statistics , AgResearch, Ruakura Research Centre , Private Bag 3123, Hamilton , New Zealand.
H V
HV
Henderson
d 27 Mansel Avenue, Hamilton 3216 , New Zealand.
N R
NR
Towers
e 153 Evans Street, Dunedin 9010 , New Zealand.
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SH
Phua
D000818:Animals; D060467:Disease Resistance / Q000235:genetics*; D006801:Humans; D026121:Indole Alkaloids; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D008129:Lolium / Q000382:microbiology*; D051379:Mice; D009154:Mutation; D009183:Mycotoxins; D055328:Neotyphodium / Q000472:pathogenicity; D012756:Sheep; D012757:Sheep Diseases / Q000235:genetics / Q000382:microbiology / Q000503:physiopathology
D026121:Indole Alkaloids; C465449:Kcnma1 protein, mouse; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D009183:Mycotoxins; C033673:lolitrem B
Review; endophyte; gene; mycotoxin; ruminant; ryegrass-staggers