Plants can turn toxic when stressed

Barley is among the 80 plant species that are prone to accumulate nitrates, which at high levels can be toxic to humans and animals. Photo: EPA

Drought and high temperatures triggered by climate change are stressing up crops. And the plants are responding by accumulating toxic substances, just like how humans react to stress.

A United Nations Environment Programme (UNEP) report, Frontiers, says stress weakens a plant and makes it disease-prone. Then, either the plant itself or invading microbes can produce chemical compounds at levels toxic to humans and animals.