Department of Molecular Biology and Plant Physiology, University of Aarhus, DK-8000 Arhus C. Denmark.
EMBO J. 1984 Aug;3(8):1691-5. doi: 10.1002/j.1460-2075.1984.tb02033.x.
During the early stages of soybean nodule development the leghemoglobin (Lb) genes are activated sequentially in the opposite order to which they are arranged in the soybean genome. At a specific stage after the initial activation of all the Lb genes, a large increment occurs in the transcription of the Lb(c1), Lb(c3) and Lb(a) genes while the transcription of the Lb(c2) gene is not amplified to a similar extent. All the Lb genes retain significant activity for a long period during the lifetime of a nodule. Consequently the soybean Lb genes are not regulated by a developmental gene switching mechanism as is the case for vertebrate globin genes. Concomitantly with the increase in Lb gene transcription some of the other nodule specific plant genes are activated. These specific changes in the activities of the Lb and nodulin genes precede the activation of the bacterial nitrogenase gene. Thus the alteration in bacterial metabolism due to nitrogen fixation is not responsible for the observed changes in the transcriptional activities of the Lb and nodule-specific genes.
在大豆根瘤发育的早期阶段，类菌体血红蛋白（Lb）基因按其在大豆基因组中排列的相反顺序依次被激活。在所有 Lb 基因最初被激活后的特定阶段，Lb(c1)、Lb(c3)和 Lb(a)基因的转录大量增加，而 Lb(c2)基因的转录则没有被扩增到类似程度。在根瘤的整个生命周期中，所有 Lb 基因都保持着很长时间的显著活性。因此，大豆 Lb 基因不受发育基因开关机制的调控，而像脊椎动物球蛋白基因那样。随着 Lb 基因转录的增加，一些其他的根瘤特异性植物基因被激活。Lb 和结瘤素基因活性的这些特定变化先于细菌固氮酶基因的激活。因此，由于固氮作用而导致的细菌代谢的改变并不是导致观察到的 Lb 和根瘤特异性基因转录活性变化的原因。
