Patel J J, Yang A F
Can J Microbiol. 1981 Jan;27(1):36-43. doi: 10.1139/m81-006.
Light and electron microscopy was used to establish the structural organisation of the developing nodule of alfalfa. In these nodules three distinct regions were noted: (1) the base region, site of original infection where the nodule is attached to the root and now composed of degenerating nodule tissue, (2) the central region, or active region composed of nodule cells containing tightly packed bacteroids surrounding a central vacuole, and (3) the meristematic region, a site of new growth, behind which newly formed cells are continually invaded. The ongoing infection process accompanying continued nodule development provided the opportunity to study the release of Rhizobium cells from the infection threads. In the nodules of alfalfa it would appear that the Rhizobium cells are released from infection thread into the nodule tissue in two different ways: (i) release with infection thread membrane and (ii) release in thin-walled vesicular structures. Thus it is concluded that Rhizobium cells are surrounded by the infection thread membrane when they are released from the infection thread into nodule tissue.
利用光学显微镜和电子显微镜来确定苜蓿发育中根瘤的结构组织。在这些根瘤中，可观察到三个不同的区域：（1）基部区域，即最初感染的部位，根瘤附着于根的此处，现在由退化的根瘤组织组成；（2）中央区域，或活跃区域，由含有紧密排列的类菌体且围绕着中央液泡的根瘤细胞组成；（3）分生组织区域，新生长的部位，在其后方新形成的细胞不断受到侵染。伴随根瘤持续发育的正在进行的感染过程为研究根瘤菌细胞从侵染线中释放提供了机会。在苜蓿根瘤中，根瘤菌细胞似乎以两种不同方式从侵染线释放到根瘤组织中：（i）与侵染线膜一起释放；（ii）在薄壁囊泡结构中释放。因此得出结论，当根瘤菌细胞从侵染线释放到根瘤组织中时，它们被侵染线膜所包围。
