Abstract
Abstract Drought stress is a major limiting factor for plant growth and development in many regions of the world. This study was designed to investigate antioxidant metabolism and dehydrin expression responses to drought stress in two switchgrass cultivars (drought tolerant Alamo, and drought sensitive Dacotah) contrasting in drought tolerance. The plants were subjected to well-watered [100% evapotranspiration (ET)] or drought stress (30%-50% ET) conditions for up to 24 d in growth chambers. Drought stress decreased leaf relative water content (RWC), increased leaf electrolyte leakage (EL), leaf malondialdehyde (MDA) content in two cultivars, but Alamo exhibited higher leaf RWC level, lower leaf EL and MDA when compared to Dacotah at 24 d of drought treatment. Drought stress also increased superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activities in two cultivars, Alamo had relatively higher SOD, CAT and APX activities and greater abundance of SOD and APX isozymes than Dacotah at 24 d of drought treatment. Alamo had higher abundance of 55 KDa and 18 KDa dehydrin accumulation than Dacotah under drought treatment. Relative genes expression level of PvCAT1, PvAPX2, PvERD and PvPIP1;5 in Alamo were significantly higher than Dacotah at 24 d of drought treatment. These results suggest that increase in antioxidant enzymes and accumulation of dehydrin were highly related with switchgrass drought tolerance. Antioxidant enzyme activity, isozyme expression and dehydrin abundance could provide a useful screening tool to identify relative drought tolerance in switchgrass cultivars.
Highlights
Drought occurs in all climates and many parts of the world every year when sufficient water needed to sustain an area is not available, causing significantly impacts on plants growth, development and crop yield [1]
A significant increase in superoxide dismutase (SOD) was observed at 18 d and 24 d of drought treatment for two cultivars compred to their control
Our previous study found that, Alamo ranked #4 in drought tolerance and Dacotah ranked #48 among 49 switchgrass lines, Alamo is a representative of good drought tolerant cultivars and Dacotah is a representative of drought sensitive ones [26]
Summary
Drought occurs in all climates and many parts of the world every year when sufficient water needed to sustain an area is not available, causing significantly impacts on plants growth, development and crop yield [1]. Worldwide losses in crop yields from drought probably exceed the losses from all other abiotic stress combined [2, 3]. Drought stresses cause oxidative stress by contributing to reactive oxygen species (ROS) such as superoxide radical (O–2), hydrogen peroxide (H2O2), hydroxyl radical (OH) and singlet oxygen (1O2) [4]. ROS may serve as a transduction signal during drought stress and improve stress defense mechanisms of plant [6]. ROS levels that are too low or too high affect plant growth and development, maintaining ROS levels within a moderate range is important for plants [7, 8]
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