High CO2 and Drought Conditions Result in Increase in Toxic Compounds, Decrease in Protein Content and Decreased Yield in Plants
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 on 29 June 2009 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.—Dr Gleadow
High Ozone Decreases Yield. In a separate paper to be presented at the meeting, researchers found that high ozone conditions cause a 30% decrease in yield and an increase in the concentration of a group of toxic compounds within oilseed rape plants. Combined with the results of previous studies which have shown a decrease in oil, protein and carbohydrate content of oilseed rape seeds in high ozone, these results could signal a significant income loss for farmers and an indirect effect on human health and the safety of food in future climates.
The research, to be presented by Maarten De Bock of the University of Antwerp, showed changes in the concentration of glucosinolates, a family of compounds involved in plant defences against herbivores, in oilseed rape plants. Such changes could influence crop resistance to insect pests, or the palatability of food crops.
As oilseed rape is important as a feed crop, increased levels of glucosinolates may cause problems due to the large quantities of fodder consumed by farm animals. For human consumption, however, an increase in glucosinolates, in cabbage plants for example, would be favorable due to their anticarcinogenic properties. Interaction of these factors and their impact on the food web in changing climates will be investigated further throughout the course of this ongoing project.