Intraspecific Variation in Metal Tolerance of Plants

Abstract

Increased heavy metal pollution of soil and water threatens agricultural plant productivity and food safety as heavy metals could enter the food chain including the edible parts (the leaves or seeds, for example) of crop plants. Classical plant breeding is based on genetic variability in many traits, including disease resistance and yield. Few studies have focused on natural variation in metal tolerance of crop and non-food plants although knowledge from such studies could lead to identification of starter germplasm for plant breeding toward development of cultivars suitable for different practical applications. These include new non-food plant varieties with enhanced metal tolerance and increased heavy metal accumulating capacity for phytoremediation or those new food crops with reduced heavy metal bioaccumulation potential to limit the threat of food safety from heavy metal contamination of food crops. In addition, studies on natural variation in tolerance to selenium (Se, an essential trace metal for the benefit of human health) among lettuce and broccoli varieties showed that Se biofortification is a promising approach. Moreover, contrasting phenotypes identified in metal toxicity screening of different varieties of a plant could be applied to aid improved understanding of metal tolerance and accumulation in plants.