Abstract
Aspartate is the most critical amino acid in the aspartate metabolic pathway, which is associated with multiple metabolic pathways, such as protein synthesis, nucleotide metabolism, TCA cycle, glycolysis, and hormone biosynthesis. Aspartate also plays an important role in plant resistance to abiotic stress, such as cold stress, drought stress, salt stress or heavy metal stress. This study found that the chlorophyll content and antioxidant active enzyme content (SOD, CAT, POD and APX) of perennial ryegrass treated with 2 mM aspartate were significantly higher than those treated with water under heat stress. The electrolyte leakage rate, MDA content and peroxide levels (O2− and H2O2) of perennial ryegrass treated with aspartate were significantly lower than those of perennial ryegrass treated with water, indicating that exogenous aspartate increases the content of chlorophyll, maintain the integrity of cell membrane system, and enhances SOD-CAT antioxidant pathway to eliminate the oxidative damage caused by ROS in perennial ryegrass under heat stress. Furthermore, exogenous aspartate could enhance the TCA cycle, the metabolism of the amino acids related to the TCA cycle, and pyrimidine metabolism to enhance the heat tolerance of perennial ryegrass.
Highlights
Heat stress, a main abiotic stress, detrimentally affects the productivity and growth of temperate plants by interrupting metabolic homeostasis and activities of various biochemical processes, such as photosynthesis, respiration, and stress defense [1]
Aspartate or aspartic acid (Asp), a basic amino acid for protein generation, serves as a central building block in nitrogen and carbon metabolism for many metabolic processes, such as the biosynthesis of other amino acids, nucleotides, organic acids in the tricarboxylic acid (TCA) cycle, sugars in glycolysis, and hormones, which are all vital for plant growth and stress resistance [3]
Given the key biofunctions of Asp as a critical metabolic hub to interconnect with diverse metabolic pathways and its reported positive effects on mitigating abiotic stresses in plants, it is hypothesized that exogenous Asp application may enhance heat endurance of cool-season grass species by activating multiple metabolic pathways involved in heat adaptation of plants
Summary
A main abiotic stress, detrimentally affects the productivity and growth of temperate plants by interrupting metabolic homeostasis and activities of various biochemical processes, such as photosynthesis, respiration, and stress defense [1]. An extensive and most recent literature review regarding how Asp affects plant reactions to diverse stresses (e.g., cold, drought, light, salinity, metal toxicity, nutrient deficiency, diseases) uncovers the essential functions of Asp in modulating plant tolerance against abiotic and biotic stresses [3]. Given the key biofunctions of Asp as a critical metabolic hub to interconnect with diverse metabolic pathways and its reported positive effects on mitigating abiotic stresses in plants, it is hypothesized that exogenous Asp application may enhance heat endurance of cool-season grass species by activating multiple metabolic pathways involved in heat adaptation of plants. This study was planned to investigate whether Asp may promote heat tolerance in perennial ryegrass, a cool-season grass species extensively utilized as forage and turfgrass, and which metabolic pathways may be regulated by Asp or are most responsive to Asp that can be associated with Asp-mediated enhancement of heat tolerance. Comparative metabolomic analysis of Asp-treated plants and control plants exposed to heat stress was conducted to recognize the Asp-modulated metabolites that may contribute to Asp-mediated enhancement of heat tolerance in perennial ryegrass
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