29/06/09 Global food security in a changing climate depends on the nutritional value and yield of staple food crops. Researchers at Monash University in Victoria, Australia have found an increase in toxic compounds, a decrease in protein content and a decreased yield in plants grown under high CO2 and drought conditions.

The research, to be presented by Dr Ros Gleadow at the Society for Experimental Biology Annual Meeting in Glasgow, has shown that the concentration of cyanogenic glycosides, which break down to release toxic hydrogen cyanide, increased in plants in elevated CO2. This was compounded by the fact that protein content decreased, making the plants overall more toxic as the ability of herbivores to break down cyanide depends largely on the ingestion of sufficient quantities of protein.

Data have also shown that cassava, a staple food crop in tropical and subtropical regions due to its tolerance of arid conditions, may experience yield reductions in high CO2. Combined with an increase in cyanogenic glycosides, this has major implications for the types of crops that can be grown in the future if CO2 levels continue to rise: "We need to be preparing for the predicted reduction in nutritional value of many plants in the coming century by developing and growing different cultivars which, for cassava in particular, may not be easy' says Dr Gleadow.