Abstract
Acibenzolar-S-methyl (ASM) is a synthetic functional analog of salicylic acid which can induce systemic acquired resistance in plants, but its effects on abiotic stress tolerance is not well known. The objectives of this study were to examine effects of acibenzolar-S-methyl on heat or drought tolerance in creeping bentgrass (Agrostis stolonifera) and to determine major ASM-responsive metabolites and proteins associated with enhanced abiotic stress tolerance. Creeping bentgrass plants (cv. ‘Penncross’) were foliarly sprayed with ASM and were exposed to non-stress (20/15°C day/night), heat stress (35/30°C), or drought conditions (by withholding irrigation) in controlled-environment growth chambers. Exogenous ASM treatment resulted in improved heat or drought tolerance, as demonstrated by higher overall turf quality, relative water content, and chlorophyll content compared to the untreated control. Western blotting revealed that ASM application resulted in up-regulation of ATP synthase, HSP-20, PR-3, and Rubisco in plants exposed to heat stress, and greater accumulation of dehydrin in plants exposed to drought stress. Metabolite profiling identified a number of amino acids, organic acids, and sugars which were differentially accumulated between ASM treated and untreated plants under heat or drought stress, including aspartic acid, glycine, citric acid, malic acid, and the sugars glucose, and fructose. Our results suggested that ASM was effective in improving heat or drought tolerance in creeping bentgrass, mainly through enhancing protein synthesis and metabolite accumulation involved in osmotic adjustment, energy metabolism, and stress signaling.
Highlights
Heat and drought stress are two major abiotic stresses limiting the growth of cool-season perennial grasses
Under heat or drought stress, turf quality (TQ), Relative water content (RWC), and CHL were significantly lower in both ASM treated and untreated control plants compared to the non-stress control
Plants which received ASM treatment had increased stress tolerance as demonstrated by lesser declines in overall visual TQ, leaf hydration status as measured by RWC, and CHL compared to untreated plants
Summary
Heat and drought stress are two major abiotic stresses limiting the growth of cool-season perennial grasses. PGRs vary in their functions of regulating different metabolic processes and in the effectiveness for plant tolerance to different type of stresses (Li et al, 1998; Zhang et al, 2003; Alcázar et al, 2010). Heat and Drought Stress in Creeping Bentgrass processes of specific PGRs involved in regulating plant tolerance to heat or drought stress is important for further knowledge of mechanisms or mode of actions of PGRs and the effective and proper use in improving plant stress tolerance. The mode of action for ASM regulation of abiotic stress tolerance is still unclear and how it alters metabolic pathways to improve stress tolerance is not well understood
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