Sitosterol-mediated Antioxidant Regulation to Enhance Heat Tolerance in Creeping Bentgrass

Abstract

Heat stress symptoms in cool-season plants are characterized by loss of chlorophyll (Chl) and membrane stability, as well as oxidative damage. The objectives of this study were to determine whether foliar application of β-sitosterol, a naturally occurring plant metabolite, may promote heat tolerance by suppressing heat-induced leaf senescence as indicated by the maintenance of healthy turf quality (TQ), and Chl and membrane stability; and to determine its roles in regulating antioxidant metabolism in creeping bentgrass (Agrostis stolonifera). ‘Penncross’ plants were exposed to heat stress (35/30 °C day/night) optimal temperature conditions (nonstressed control, 22/17 °C day/night) for a duration of 28 days in environment-controlled growth chambers. Plants were foliar-treated with β-sitosterol (400 µM) or water only (untreated control) before heat stress, and at 7-day intervals through 28 days of heat stress. Plants treated with β-sitosterol had significantly greater TQ and Chl content, and significantly less electrolyte leakage (EL) than untreated controls at 21 and 28 days of heat stress. Application of β-sitosterol reduced malondialdehyde (MDA) content significantly at 21 and 28 days of heat stress, and promoted the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) from 14 through 28 days of heat stress. β-Sitosterol effectively improved heat tolerance through suppression of leaf senescence in creeping bentgrass exposed to heat stress in association with the alleviation of membrane lipid peroxidation and activation of the enzymatic antioxidant system.

The influence of chitosan on plant growth and -sitosterol content in adventitious roots of Talinum paniculatum in NFT hydroponic cultivation system

“…Another stress factor known to induce b-sitosterol production is heat from excessively high temperatures (Rossi and Huang, 2019). The temperature range during the research was maintained between 25 o C and 27 o C, whereas the literature suggests that the temperature threshold for inducing such stress can reach up to 35 o C (Rossi and Huang, 2019). In other words, there was no heat stress due to the high temperatures used in this research.…”

“…Additionally, chitosan enhances water absorption in plants, preventing them from experiencing drought conditions (Chakraborty et al, 2020). Another stress factor known to induce b-sitosterol production is heat from excessively high temperatures (Rossi and Huang, 2019). The temperature range during the research was maintained between 25 o C and 27 o C, whereas the literature suggests that the temperature threshold for inducing such stress can reach up to 35 o C (Rossi and Huang, 2019).…”

Biosynthesis and the Roles of Plant Sterols in Development and Stress Responses

“…For instance, tomato seeds soaked with 10 µM sitosterol showed distinctly promoted tolerance of tomato plants to both high and low temperature stress [87]. Similarly, the treatment of Agrostis stolonifera leaves with 400 µM sitosterol resulted in the inhibition of leaf senescence, the enhancement of membrane stability as well as the activation of plant antioxidant responses under heat stress, and ultimately enhanced plant heat tolerance [88].…”