Differential Heat‐Induced Changes in Phenolic Acids Associated with Genotypic Variations in Heat Tolerance for Hard Fescue
2019
Wang, Jinyu | Yuan, Bo | Huang, Bingru
Secondary metabolites, including phenolic acids, play important roles in plant defense against abiotic stress. The objectives of this study were to evaluate the response of phenolic acids to short‐term heat shock (7 h) and long‐term heat stress (21 d) in hard fescue [Festuca trachyphylla (Hack.) Krajina] and to identify constituents of phenolic acids associated with genotypic variation in heat tolerance. Plants of the heat‐tolerant cultivar ‘Reliant IV’ and heat‐sensitive cultivar ‘Predator’ were exposed to heat stress at 38/33°C (day/night) or nonstress temperature conditions at 22/18°C. Four phenolic acids (salicylic acid, homovanillic acid, caffeic acid, and ferulic acid) showed significant increases in content under short‐term heat shock. Seven phenolic acids (3,4‐dyhydroxybenzoic acid, 4‐hydroxybenzoic acid, coumaric acid, gallic acid, cinnamic acid, benzoic acid, and vanillic acid) showed significant increases in content after long‐term heat stress. Increases in the content of homovanillic acid (by 118%) and caffeic acid (by 117%) were observed in Reliant IV under short‐term heat shock compared with the untreated control, whereas 3,4‐dyhydroxybenzoic acid showed greater accumulation in Reliant IV (by 214%) than Predator (by 148%) under long‐term heat stress. These differentially accumulated phenolic acids could be associated with the contrasting levels of heat tolerance between the two cultivars. The transient increases in response to short‐term heat shock indicate their potential roles as stress signaling molecules, and their dramatic accumulation after long‐term heat stress suggests protective roles under heat stress.
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