US EPA

191585 

Journal Article 

Ozone phytotoxicity and plant defense responses 

Patil, VU 

2007 

1 

Research Journal of Biotechnology
ISSN: 0973-6263 

2 

4 

49-54 

WOS:000254833500010 

http://www.chemenviron.org/environ/rjbt/bk_issue/cont-4-07.htm
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Global atmospheric concentrations have risen about 36% since the preindustrial times. Rapid industrialization and human activities have contributed significant amounts of this toxic gas pollutant to the tropospheric environment that pose significant threat for the survival and productivity of native and cultivated ecosystems. Currently 25% of the global forests are at the risk from damaging ozone concentrations (>60 ppb) and it is predicted to increase to 50% by 2100. Stratospheric ozone shields biologically harmful UV radiations from reaching the earth's surface, however, somewhat paradoxically; tropospheric ozone is toxic to biological organisms. Ozone is one of the most powerful oxidizing agents. In plants primary damage by ozone is largely confined to leaf mesophyll (major productive unit). Ozone on reaction with water and solutes forms Reactive Oxygen Species (ROS), triggering the oxidative burst in plants. The effects of ozone on plants are numerous and vary with the intensity and duration of the exposure. Ozone induces hypersensitivity response (HR) and ultimately induces the-programmed cell death leading to reduced rate of photosynthesis. The present study deals with the various plant cells signalling pathways induced by ozone, which ultimately lead to the programmed cell death and also various secondary signalling molecules in the plant cell. 

defense response; oxidative burst; ozone stratosphere; troposphere