Effect of abiotic stress on synthesis of secondary plant products: a critical review

Drought and salinity are serious threats to agriculture and natural physico-biochemical status of plants metabolism. Generally, plants show an ability to adopt their metabolism to changes in environment. They synthesize an array of secondary products with economic value in normal environment but, however, several stress factors can results in increased their production. As a fact that under stress conditions, a strong oversupply of reduction equivalents (NADPH+H⁺) is produced. An analysis suggests that amount of secondary plant products is higher in plants, severely affected from abiotic stress than plants grown under optimal conditions. In order to reduce damage by ROS, NADPH+H⁺ is re-oxidized by photorespiration and violaxanthine cycle. Yet, the higher concentration of reduction equivalents proceeds to growth of reduced secondary metabolites. In this review, we targeted special emphasis on quality and quantity aspects of improvement by enhancing the average level of plant metabolites possess economic value, by deliberately applying stresses.