Zablotowicz Robert M, Reddy Krishna N
USDA Agricultural Research Service, Southern Weed Science Research Unit, Stoneville, MS 38776, USA.
J Environ Qual. 2004 May-Jun;33(3):825-31. doi: 10.2134/jeq2004.0825.
Glyphosate-resistant (GR) soybean [Glycine max (L.) Merr.] expressing an insensitive 5-enolpyruvylshikimic acid-3-phosphate synthase (EPSPS) gene has revolutionized weed control in soybean production. The soybean nitrogen fixing symbiont, Bradyrhizobium japonicum, possesses a glyphosate-sensitive enzyme and upon exposure to glyphosate accumulates shikimic acid and hydroxybenzoic acids such as protocatechuic acid (PCA), accompanied with B. japonicum growth inhibition and death at high concentrations. In a series of greenhouse and field experiments, glyphosate inhibited nodulation and nodule leghemoglobin content of GR soybean. Glyphosate accumulated in nodules of field-grown GR soybean, but its effect on nitrogenase activity of GR soybean was inconsistent in field studies. In greenhouse studies, nitrogenase activity of GR soybean following glyphosate application was transiently inhibited especially in early growth stages, with the greatest inhibition occurring under moisture stress. Studies using bacteroid preparations showed that the level of glyphosate inhibition of bacteroid nitrogenase activity was related to in vitro glyphosate sensitivity of the B. japonicum strains. These studies indicate the potential for reduced nitrogen fixation in the GR soybean system; however, yield reductions due to this reduced N2 fixation in early stages of growth have not been demonstrated.
表达不敏感的5-烯醇丙酮酰莽草酸-3-磷酸合酶（EPSPS）基因的抗草甘膦（GR）大豆[Glycine max (L.) Merr.]彻底改变了大豆生产中的杂草控制方式。大豆的固氮共生体——日本慢生根瘤菌，拥有一种对草甘膦敏感的酶，接触草甘膦后会积累莽草酸和羟基苯甲酸，如原儿茶酸（PCA），在高浓度下会伴随日本慢生根瘤菌的生长抑制和死亡。在一系列温室和田间试验中，草甘膦抑制了GR大豆的结瘤和根瘤豆血红蛋白含量。草甘膦在田间种植的GR大豆根瘤中积累，但其对GR大豆固氮酶活性的影响在田间研究中并不一致。在温室研究中，施用草甘膦后GR大豆的固氮酶活性会受到短暂抑制，尤其是在生长早期，在水分胁迫下抑制作用最大。使用类菌体制剂的研究表明，草甘膦对类菌体固氮酶活性的抑制水平与日本慢生根瘤菌菌株的体外草甘膦敏感性有关。这些研究表明GR大豆系统中存在固氮减少的可能性；然而，尚未证实生长早期因这种固氮减少而导致的产量下降。
