ABSTRACT
Use of triazine-resistant crops could provide an effective and economical method of controlling many related cruciferous weed species such as wild mustard and stinkweed that otherwise were very difficult, if not impossible to control. Photosynthetic electron flow occurs in the stacked and unstacked thylakoid membranes within the chloroplast organelles. The electron transport from water to NADP+ requires the participation of three membrane-spanning multiprotein complexes: the photosystem II (PS II) complex, the cytochrome b6/f complex, and the photosystem I (PS I) complex. Trebst divided PS II herbicides into two families: those that bind to the Dl protein near Ser 264, such as the triazines and ureas, and those that bind at His 215, such as the nitrophenols. Varying degrees of cross-resistance to the uracils, pyridazinones, and certain ureas exist in triazine-resistant plants. Negative-cross resistance occurs when herbicides, other than the one to which the plant has developed resistance, become more toxic to the resistant biotype than to the susceptible biotype.
