Matringe Michel, Sailland Alain, Pelissier Bernard, Rolland Anne, Zink Olivier
Laboratoire de Physiologie Cellulaire Végétale, CNRS (UMR 5168)-CEA-Université Joseph Fourier-INRA (UMR 1200), CEA-Grenoble, 38054 Grenoble Cedex 9, France.
Pest Manag Sci. 2005 Mar;61(3):269-76. doi: 10.1002/ps.997.
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.
对羟基苯丙酮酸双加氧酶（HPPD）催化尿黑酸的形成，尿黑酸是质体醌和维生素E的芳香族前体。HPPD是几个除草剂家族的特异性作用靶标：异恶唑类、三酮类和吡唑类。对它的抑制会导致植物质体醌和维生素E库的耗尽，从而引发白化症状。这些除草剂对于玉米和水稻中多种阔叶杂草和禾本科杂草的选择性苗前以及在某些情况下的苗后防除非常有效。它们的除草潜力引发了人们对培育高抗性转基因作物的兴趣。这一目标首先通过在作物中过量表达一种细菌HPPD得以实现，而通过使用一种突变酶则获得了更高水平的抗性。随后开发了第二种策略，即在尿黑酸的生产过程中绕过HPPD。最近，又开发了第三种基于增加对羟基苯丙酮酸底物通量的抗性策略。这是通过将酵母预苯酸脱氢酶基因（PDH）导入已经过量表达HPPD的转基因植物中来实现的。除了具有高水平的除草剂抗性外，在转基因HPPD-PDH植物的叶片中还观察到了维生素E的大量积累，主要是生育三烯酚。
