Zabalza Ana, Gaston Susana, Ribas-Carbó Miquel, Orcaray Luis, Igal Maria, Royuela Mercedes
Departamento de Ciencias del Medio Natural, Universidad Pública de Navarra, E-31006 Pamplona, Spain.
J Agric Food Chem. 2006 Nov 15;54(23):8818-23. doi: 10.1021/jf0618224.
The pattern of nitrogen assimilation in soybean plants treated with a herbicide that inhibits branched-chain amino acid biosynthesis was evaluated by (15)N isotopic analysis. The herbicide imazethapyr caused a strong decrease in nitrate uptake by roots, partly due to a reduced stomatal conductance. The inhibition of (15)N uptake was accompanied by a decrease in the (15)N content in the plant and, concomitantly, an inhibition of translocation to the shoot. Imazethapyr inhibited nitrate reductase activity in leaves and roots. Among all parameters studied, "de novo" synthesis of proteins was the first parameter of the N assimilation metabolism affected by the herbicide. These results show that this class of herbicides totally damages N metabolism and indicates a regulatory effect on N uptake and translocation that would be mediated by the increase in free amino acid pool provoked by the inhibition of branched-chain amino acid biosynthesis.
通过¹⁵N同位素分析评估了用抑制支链氨基酸生物合成的除草剂处理的大豆植株中氮同化模式。除草剂咪草烟导致根系对硝酸盐的吸收大幅下降，部分原因是气孔导度降低。¹⁵N吸收的抑制伴随着植株中¹⁵N含量的下降，同时，向地上部的转运也受到抑制。咪草烟抑制了叶片和根系中的硝酸还原酶活性。在所有研究的参数中，蛋白质的“从头”合成是受除草剂影响的氮同化代谢的第一个参数。这些结果表明，这类除草剂完全破坏了氮代谢，并表明对氮吸收和转运有调节作用，这种调节作用将由支链氨基酸生物合成受抑制引发的游离氨基酸库增加介导。
