p‐Hydroxyphenylpyruvate dioxygenase inhibitor‐resistant plants

Abstract

The enzyme p-hydroxyphenylpyruvate dioxygenase (HPPD) catalyzes the formation of homogentisic acid, the aromatic precursor of plastoquinone and vitamin E. HPPD is the specific target of several herbicide families: isoxazoles, triketones and pyroxazoles. Its inhibition results in the depletion of the plant plastoquinone and vitamin E pools, leading to bleaching symptoms. These herbicides are very potent for the selective pre- and in some cases post-emergence control of a wide range of broadleaf and grass weeds in maize and rice. Their herbicidal potential raised interest in the development of highly resistant transgenic crops. This goal was first achieved by over-expression of a bacterial HPPD in crop plants, and an increased level of resistance was obtained by using a mutant enzyme. A second strategy based on bypassing HPPD in the production of homogentisate was then developed. Recently, a third strategy of resistance based on the increase of p-hydroxyphenylpyruvate substrate flux has been developed. This was achieved by the introduction of the yeast prephenate dehydrogenase gene (PDH) into transgenic plants already overexpressing HPPD. In addition to a high level of herbicide resistance, a massive accumulation of vitamin E, mainly tocotrienols, was observed in leaves of the transgenic HPPD-PDH plants.

Distinct Detoxification Mechanisms Confer Resistance to Mesotrione and Atrazine in a Population of Waterhemp

“…Molecular information regarding plant HPPD gene sequences and expression patterns is limited (for review, see Pallett, 2000;Kim and Petersen, 2002;Riechers and Stanford, 2002;Matringe et al, 2005), and only a single expressed HPPD gene was detected in waterhemp (Riggins et al, 2010). Herbicidal activity of mesotrione in sensitive plants is due to competitive inhibition of the HPPD enzyme, which is a key enzyme in the biosynthesis of tocopherols and plastoquinone.…”

Broad 4-Hydroxyphenylpyruvate Dioxygenase Inhibitor Herbicide Tolerance in Soybean with an Optimized Enzyme and Expression Cassette

“…Two transgenic soybean crop products, one for tolerance to isoxaflutole (APHIS, 2009) and the other to mesotrione and isoxaflutole (APHIS, 2012), are in the U.S. Department of Agriculture deregulation approval process. The former uses a Pseudomonas fluorescens HPPD with a single amino acid change (Matringe et al, 2005), while the latter uses HPPD from oat (Avena sativa) with a single amino acid change (Hawkes et al, 2010). Our goal was to develop soybean lines with tolerance to a broad spectrum of HPPD inhibitors.…”

Convenient screening of 4-hydroxyphenylpyruvate dioxygenase inhibitors by UV absorbance detection in the presence of Fe2+ ion

“…[1][2][3][4] The enzyme is the molecular target site for one of the bleaching herbicides having a 1,3-diketone moiety for herbicidal activity, for example, pyrazolate (4-(2,4-dichlorobenzoyl)-1,3-dimethylpyrazol-5-yl p-toluenesulfonate), benzobicyclone (3-[2-chloro-4-(methylsulfonyl)benzoyl]-4-(phenylthio)bicyclo[3.2.1]oct-3-en-2-one) and isoxaflutole (5-cyclopropyl-4-(2-methylsulfonyl-4-trifluoromethylbenzoyl)isoxazole). [5][6][7] These inhibitors caused a reduction in the plastoquinone level in plants as its main herbicidal effect.…”