JXB Advance Access published online on October 26, 2007
Journal of Experimental Botany, doi:10.1093/jxb/erm227
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RESEARCH PAPER |
Physiological basis of different allelopathic reactions of cucumber and figleaf gourd plants to cinnamic acid
1Department of Horticulture, Huajiachi Campus, Zhejiang University, Kaixuan Road 268, Hangzhou, PR China 310029
2Key Laboratory of Horticultural Plant Growth, Development and Biotechnology, Agricultural Ministry of China, Kaixuan Road 268, Hangzhou, PR China 310029
* To whom correspondence should be addressed. E-mail: jqyu{at}zju.edu.cn
To provide an insight into the mechanism of interspecific interactions mediated by allelochemicals, cucumber and figleaf gourd seedlings were compared on their response to cinnamic acid, an autotoxin from root exudates of cucumber. Reactive oxygen species metabolism and plasma membrane H+-ATPase activity were examined in roots upon exposure to cinnamic acid. This exposure resulted in significant increases in activities of NADPH oxidase, superoxide dismutase, guaiacol peroxidase, and catalase, as well as in O
production and H2O2 content, in cucumber roots but not in figleaf gourd roots. Notably, the cucumber roots produced significant amount of reactive oxygen species (ROS) immediately after cinnamic acid treatment, consequently increasing membrane peroxidation, decreasing membrane H+-ATPase activity, and losing root viability. By contrast, no such changes were observed in figleaf gourd roots. All these results indicated that there was an interspecies difference in the recognition of allelochemicals, which induced oxidative stress accompanied by root cell death in cucumber, an autotoxic plant, but not in figleaf gourd, a cucumber relative.
Key words: Allelochemical, autotoxicity, cell viability, H+-ATPase, reactive oxygen species, oxidative stress, specific recognition
Received 13 June 2007; Revised 15 August 2007 Accepted 22 August 2007