The Mode of Action of Isoxaflutole

Tocopherol as singlet oxygen scavenger in photosystem II

“…The scheme is extended with tocopherol biosynthesis, inhibition at the hydroxyphenylpyruvate dioxygenase (HPPD), and singlet oxygen scavenging by tocopherol or quenching by diphenylamine (Trebst, 2003). crop control, isoxaflutole (Lee et al, 1997;Pallett et al, 1998) and pyrazolynate (Matsumoto et al, 2002) are also active inhibitors in the algae Chlamydomonas, whereas sulcotrione (Schulz et al, 1993) is not. Both isoxaflutole and pyrazolynate are used in commercial preparations in a chemically protected form which is hydrolyzed in plants to the active component.…”

Novel vitamin E forms in leaves of Kalanchoe daigremontiana and Phaseolus coccineus

“…In order to find the possible substrates for ␥-tocomonoenol synthesis, isoxaflutole, an inhibitor of homogentisate synthesis (Pallet et al, 1998) was used, and it inhibited the light-induced increase in ␥-tocomonoenol synthesis, while homogentisate stimulated it in the dark (Fig. 8).…”

Reversal of the inhibition of photosynthesis by herbicides affecting hydroxyphenylpyruvate dioxygenase by plastoquinone and tocopheryl derivatives inChlamydomonas reinhardtii

“…A group of recently discovered herbicides, including isoxaflutole, pyrazolate and sulcotrione, are inhibitors of HPP dioxygenase,1–5 an enzyme that oxidises hydroxyphenylpyruvate to homogentisate in the biosynthesis of plastoquinone and tocopherol. The bleaching effect of these herbicides on plants is thought to be due to a plastoquinone deficiency in the phytoene desaturase, which leads to a shortage in carotenoid biosynthesis for protection of photosynthesis 3–6. We have recently described, in the green alga Chlamydomonas reinhardtii Dang, a system in which pyrazolate and isoxaflutole addition resulted in a massive tocopherol loss when the algae were exposed for a short time to very high light 7.…”