Dehydration Avoidance and Damage to the Plasma and Thylakoid Membranes in Lines of Maize Differing in Endogenous Levels of Abscisic Acid

Abstract

Dehydration avoidance and damage to the plasma and thylakoid membranes were studied in the high-ABA, drought-resistant line of maize ZPBL 1304 and the low-ABA, drought-sensitive line ZPL 389 after exposure to soil drying and high-temperature (45 °C) stress conditions. Thirteen-day-old plants were exposed to 7-d soil drying followed by either 6-h or 24-h high-temperature stress. The high-ABA line ZPBL 1304 was affected by 7-d soil drying followed by 6-h heat stress to a limited extent. The low-ABA line ZPL 389 was affected by 7-d soil drying followed by 6-h heat stress to a great extent, but showed the ability to recover after stress. Extended heat treatment (24 h) affected line ZPBL 1304 reversibly, but was lethal to almost all plants in line ZPL 389. Line ZPBL 1304 showed much greater ability to avoid dehydration and damage to the plasma membrane than line ZPL 389. The stress effects on the stability of thylakoid membranes in lines ZPBL 1304 and ZPL 389 were similar but only when ZPBL 1304 was exposed to high-temperature treatment for a period 4 times longer than ZPL 389. The results support the hypothesis that higher levels of endogenous ABA can indicate drought and heat resistance in maize.