Physiological and molecular responses of maize (Zea mays L.) plants to drought and rehydration

Physiological and molecular responses of maize seedlings (Zea mays L. cv. Troinaya sladost) to 5-d drought and rehydration for 48 h were investigated. Plant water status was determined by a new method of water potential measurement in mesophyll cells' apoplast in substomatal cavity (psi(wa)). Drought caused the changes in water status, plant growth, the rates of photosynthetic CO2/H2O gas exchange, and metabolism of carbohydrates and proline. The increase in carbohydrate and proline content under drought was observed simultaneously with the decline in psi(wa). Rewatering of seedlings for 24 and 48 h resulted in restoration of growth, rapid increase in psi(wa) as well as in the rates of photosynthetic gas exchange, and a sharp decline in the content of soluble sugars and proline. Data on close correspondence between the changes in osmolyte content and psi(wa) under drought and recovery support the assumption that osmolytes might participate in regulation of psi(wa).