Metabolic response of maize (Zea mays L.) plants to combined drought and salt stress

Maize is exposed to the combined stresses of water deficiency and soil salinity within its natural habitat, particularly in irrigated and dry land agricultural areas. Hence, the effect of these combined stresses on the metabolic response of maize plants was determined to improve understanding of stress tolerance mechanisms of maize in the field. Maize plants were either singly or simultaneously exposed to soil water deficiency and high salinity for 7 d. Physiological characteristics were analyzed and metabolic changes were quantified by conducting H-1 NMR-based analysis of polar and non-polar fractions of maize leaf extracts. The response of maize plants to the combined stresses was distinct from that of plants subjected to either drought stress or salt stress alone at both the metabolic and physiological level. Maize plants showed a new pattern of metabolic response to the combined stresses. Some metabolites specifically responded to combined stresses and differed from those caused by each stress applied individually. The global metabolic response of maize to the combined stresses was related to the physiological processes. Our results provide valuable insights into the response of maize to combined drought and salt stress by linking stress-related physiological responses to changes in metabolites.