Oxidative stress and plant responses to pathogens under drought conditions

Abstract

Increase in global temperature has resulted in a decrease in summer precipitation and created mild and severe drought conditions, especially in semi-arid and arid environments. Drought might cause direct or indirect physiological and biochemical damages to crop plants, which results in loss of crop quality and production. Under drought conditions, not only do crop plants suffer from the scarcity of water but the plant pathogens might adapt or act as still pathogens under drought conditions. They could synthesize more toxins and pathogenic cell wall degrading enzymes. The impact of pathogenicity could increase on crop plants via increased virulence levels. The havoc of plant pathogens under drought conditions could therefore be more devastating due to reduced defence systems in crop plants. In severe drought cases, both plant pathogens and crop plants might be negatively affected, however, plant pathogens might tolerate negative effects of drought. Then double stress arising from both abiotic and biotic stress on plant metabolism is inevitable. In prolonged drought stress conditions, drought tolerant or halophytic races of plant pathogens might appear and infect the crop plants, and tolerate the negative effects of drought stress easily, then becoming a major threat to crop plants even in well-watered agricultural areas. Therefore, pathogen behaviour under water stress conditions should be carefully evaluated and not be neglected while a generation of stress tolerant plants has been created. Teams of breeders, physiologists, molecular geneticists, agronomists, pathologists, biochemists and statisticians should tackle the challenge of producing enough food with insufficient water resources. New breeding programmes to combat future disease problems under drought stress need to be multi-factorial to become successful.