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ABSTRACT
β-cembrenediol ((1S, 2E, 4R, 6R, 7E, 11E)-2, 7, 11 -cembratriene-4,6-diol), shown to be one of the most important allelochemicals of tobacco in previous studies, effectively inhibited the root and stem growth of receptor plants and the inhibitory effects was concentration-dependent. However, its mechanism of action remains unclear. Seedlings of lettuce (Tai Yuan Sun) were treated with β-cembrenediol to clarify its mode of action. Results showed that β-cembrenediol significantly inhibited the seedling growth and reduced fresh weight of L. sativa. The compounds effectively affected cell mitotic index and caused cell death. Exposure to β-cembrenediol induced overproduction of reactive oxygen species (ROS). Moreover, increased content of hydrogen peroxide, malondialdehyde, and proline, and decreased in chlorophyll content indicated lipid peroxidation and induction of oxidative stress. These results suggested that β-cembrenediol caused oxidative damage through enhanced generation of ROS, as indicated by increased lipid peroxidation, disruption of membrane integrity and impacted mitosis, ultimately resulted in growth inhibition of the receptor plant.
Keywords: β-Cembrenediol; Phytotoxicity; Lettuce; Oxidative stress; Reactive oxygen species
INTRODUCTION
Allelopathy is a natural ecological phenomenon which involves the release of plant-produced secondary products (allelochemicals) into the environment by volatilization, root exudation, decomposition and/or leaching (Pan et al., 2015). It influences the growth and development of neighboring plants or itself (Cruz-Ortega et al., 2007; Babula et al., 2009; Rial et al., 2014; Kimura et al., 2015; Pan et al., 2015). Many aspects of plant physiological and biochemical processes, such as the cell cycle, phytohormone metabolism, reactive oxygen species generation and plant photosynthesis could thus be affected (Weir et al. 2004; Gniazdowska and Bogatek., 2005; Ding et al.,2007; Babula et al., 2009; Ding et al., 2016). Recent findings showed that allelochemical stress was similar in action to that of pathogens (biotic stress) or herbicides (abiotic stress), in that it increases the concentration of reactive oxygen species (ROS) in plant cells (Golisz et al., 2007; Su et al., 2016). The ROS subsequently leads to oxidative damage, increases the degree of membrane lipid peroxidation, and ultimately results in the death of cells (Ye et al., 2006; Yan et al., 2015).
The tobacco plant, a member of the Solanaceae family, is an important cultured and economic crop over the world. Extracts of this plant have been reported to have a...