Photosysthem ii inhibitors: an allelochemical perspective

The process of photosynthesis involves the absorption of light energy by photosynthetic pigments found in the thylakoid membrane of chloroplasts in order to produce chemical energy. In the presence of photosynthetic inhibitors, plant development is affected mainly by the reduction of the electron chain, which leads to growth inhibition. In this context, chlorophyll a (Chl a) fluorescence is an important technique used to identify the effects of inhibitors on the photosynthetic apparatus employing the JIP-test, which correlates the Chl a fluorescence transient to biophysical parameters, providing valuable information about the efficiency of photosystems I and II. Natural products have been highlighted as photosynthesis inhibitors due to the continued use of synthetic herbicides, which leads to the development of invasive plants resistant to these pesticides, in addition to the toxicity caused to humans and the environment. Thus, this review describes the main applications of extracts and isolated secondary metabolites obtained from plants and microorganisms in the investigation of electron transport inhibition on photosystem II.