Ördög Vince, Molnár Zoltán (2011)
Debreceni Egyetem, Nyugat-Magyarországi Egyetem, Pannon Egyetem
The use of herbicides to kill unwanted plants is widespread in modern agriculture. Some herbicides, like dichlorophenyldimethylurea (DCMU, also known as diuron) and paraquat, block photosynthetic electron flow (Figure 2.20). DCMU blocks electron flow at the quinone acceptors of photosystem II, by competing for the binding site of plastoquinone that is normally occupied by PQB. Paraquat accepts electrons from the early acceptors of photosystem I and then reacts with oxygen to form superoxide, O2-, a species that is very damaging to chloroplast components, especially lipids.
Figure 2.20 Chemical structure and mechanism of action of two important herbicides (source: Taiz L., Zeiger E., 2010)