The role of proline-associated pentose phosphate pathway in cool-season turfgrasses after UV-B exposure

Physiological adjustments of cool-season turfgrasses were investigated to determine the role of proline-associated pentose phosphate pathway for phenolic biosynthesis and stimulation of antioxidant response system following UV-B exposure. Creeping bentgrass, Kentucky bluegrass, tall fescue, and perennial ryegrass plugs were subjected to artificial UV-B exposure (biologically effective UVBBE radiation 8 kJ m−2 d−1.) for one week with 10-h photoperiod. Significant accumulation of phenolics and stimulation of antioxidant enzyme activity was observed in all investigated cool-season turfgrasses after UV-B exposure and this induction corroborated with higher glucose-6-phosphate dehydrogenase activity and high accumulation of proline. Guaiacol peroxidase activity also increased in all investigated cool-season turfgrass species after UV-B exposure. In this study, the shift of carbon flux from glycolysis to pentose phosphate pathway following UV-B exposure and as a result of that, the higher accumulation of phenolics and stimulation of antioxidant response system provides an insight to understand a probable defense mechanism of cool-season turfgrasses against UV stress.

Research highlights▶ There is very limited understanding regarding physiological mechanisms to UV responses in cool-season turfgrasses. ▶ So, our overall research goal was to evaluate whether UV-B exposure could cause an upregulation of the pentose phosphate pathway and stimulation of phenolic-linked antioxidant enzyme response in cool-season turfgrasses. ▶ We hypothesized that proline-associated pentose phosphate pathway may play a crucial role under UV-B stress in turfgrass species and as a result of this; phenolic phytochemicals can effectively counter oxidative stress within cells. ▶ This research has shown the significant accumulation of phenolics and stimulation of antioxidant enzyme activity in all investigated cool-season turfgrasses after UV-B exposure and this induction corroborated with higher glucose-6-phosphate dehydrogenase activity and high accumulation of proline. ▶ Guaiacol peroxidase activity also increased in all investigated cool-season turfgrass species after UV-B exposure. ▶ Further, the shift of carbon flux from glycolysis to pentose phosphate pathway following UV-B exposure and as a result of that, the higher accumulation of phenolics and stimulation of antioxidant response system provides an insight to understand a probable defense mechanism of cool-season turfgrasses against UV stress.