Short-term UV-B radiation effects on morphology, physiological traits and accumulation of bioactive compounds in Prunella vulgaris L.

Xue-Rong Zhang,Yu-Hang Chen,Qiao-Sheng Guo,Wen-Ming Wang,Li Liu,Jin Fan,Li-Ping Cao,Chen Li

doi:10.1080/17429145.2017.1365179

Abstract

ABSTRACTPrunella vulgaris plants (full-bloom stage) were subjected to short-term (15 days) UV-B radiation in a growth chamber. UV-B radiation was effective at enhancing morphological and biomass characteristics and decreasing chlorophyll contents of P. vulgaris. Treatment of P. vulgaris with artificial UV-B radiation significantly increased peroxidase (POD), superoxide dismutase (SOD) and glutathione (GSH) activities compared to the control treatment. UV-B radiation significantly increased the levels of hydrogen peroxide (H2O2), malondialdehyde (MDA) and proline in leaves of P. vulgaris compared to those of control plants. In addition, the contents of total flavonoids, rosmarinic acid, caffeic acid and hyperoside significantly increased under UV-B radiation. The total phenolic levels also increased under UV-B treatment. These results demonstrated that short-term UV-B radiation can enhance production of secondary metabolites in P. vulgaris, resulting in increased spica yield compared to that of control plants.

Highlights

In recent years, depletion of the stratospheric ozone layer because of atmospheric pollutant sources such as bromineand chlorine-containing compounds has led to an increase in ultraviolet-B radiation (UV-B) reaching the earth’s surface (Bjorn 1996; McKenzie et al 2003)
Previous studies have reported that UV-B radiation is a serious environmental stress that enhances the generation of reactive oxygen species (ROS), including superoxide radicals (O2−), hydrogen peroxide (H2O2), singlet oxygen (1O2) and hydroxyl radicals (OH) (Mackerness et al 1998; He and Hader 2002)
Our study showed that the increased proline content from UV-B exposure may offer P. vulgaris plants protection against ROS generated by the UV-B radiation

Summary

Introduction

Depletion of the stratospheric ozone layer because of atmospheric pollutant sources such as bromineand chlorine-containing compounds has led to an increase in ultraviolet-B radiation (UV-B) reaching the earth’s surface (Bjorn 1996; McKenzie et al 2003). Several studies have indicated the harmful influence of UV-B radiation, leading to leaf discoloration, plant stunting and reductions in leaf area, leaf number, biomass and plant productivity (Frohnmeyer and Staiger 2003). Previous studies have reported that UV-B radiation is a serious environmental stress that enhances the generation of reactive oxygen species (ROS), including superoxide radicals (O2−), hydrogen peroxide (H2O2), singlet oxygen (1O2) and hydroxyl radicals (OH) (Mackerness et al 1998; He and Hader 2002). Plants respond to oxidative damage by activating their antioxidant metabolism, including activation of the enzymes superoxide dismutase (SOD) and peroxidase (POD), which scavenge ROS and offer protection to nucleic acids, lipids and proteins (Jain et al 2004; Zu et al 2010). UV-Babsorbing compounds mainly protect the DNA (Stapleton 1992), these compounds play a key role in the plant antioxidative defense system and against herbivores and pathogens (Ortuñoa et al 2006; Hagen et al 2007; Agrawal et al 2009)

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