Abstract
Trehalose (Tre) and salicylic acid (SA) are increasingly used to mitigate drought stress in crop plants. In this study, a pot experiment was performed to study the influence of Tre and SA applied individually or in combination on the growth, photosynthesis, and antioxidant responses of sweet basil (Ocimum basilicum L.) exposed to drought stress. Basil plants were watered to 60% or 100% field capacity with or without treatment with 30 mM Tre and/or 1 mM SA. Drought negatively affected growth, physiological parameters, and antioxidant responses. Application of Tre and/or SA resulted in growth recovery, increased photosynthesis, and reduced oxidative stress. Application of Tre mitigated the detrimental effects of drought more than SA. Furthermore, co-application of Tre and SA largely eliminated the negative impact of drought by reducing oxidative stress through increased activities of antioxidant enzymes superoxide dismutase, peroxidase, and catalase, as well as the accumulation of the protective osmolytes proline and glycine betaine. Combined Tre and SA application improved water use efficiency and reduced the amount of malondialdehyde in drought-stressed plants. Our results suggested that combined application of Tre and SA may trigger defense mechanisms of sweet basil to better mitigate oxidative stress induced by drought stress, thereby improving plant growth.
Highlights
Under the threat of climate change, crop production is predicted to become more challenging due to increasing severity of various abiotic stresses [1,2]
A reduction in electron transport chain (ETC) activity during drought stress leads to accumulation of reactive oxygen species (ROS) that are toxic at elevated levels [8]
The combined application of Tre + salicylic acid (SA) to drought-stressed plants resulted in shoots and roots that were 39% and 36% longer, respectively, than in unsprayed drought
Summary
Under the threat of climate change, crop production is predicted to become more challenging due to increasing severity of various abiotic stresses [1,2]. Drought stress is the leading ecological constraint to plant growth. It is the most critical concern, especially in the face of current scenarios of global warming [1], and it is predicted to become more frequent in numerous regions of the world [3]. A reduction in electron transport chain (ETC) activity during drought stress leads to accumulation of reactive oxygen species (ROS) that are toxic at elevated levels [8]. These oxidizing compounds react with and damage nucleic acids, proteins, photosynthetic pigments, and membrane lipids [9]. Plants acclimate to ROS-induced stress by producing various beneficial compatible solutes, such as proline and glycine betaine [10,11]
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