红豆草根瘤侵入线的超微结构研究

Ultrastructural Studies of the Infection Threads in Onobrychis viciaefolia Root Nodules

用透射电镜对红豆草根瘤侵入线的超微结构进行了观察研究.结果表明,(1)红豆草根瘤侵入线由胞间隙和胞间层细胞壁内陷形成,它们的体积较小,多为管状,基质丰富,含菌很少,常有分叉和1个以上的基质区,而且不同基质区的电子密度、细菌数量和侵入线壁厚度都不相同.(2)红豆草根瘤的侵入线十分丰富,它们不仅大量存在于根瘤分生细胞和幼龄侵染细胞中,也经常出现在发育成熟的侵染细胞内.(3)红豆草根瘤中有一种近似圆形的特殊结构,表面由一层膜包围,其内电子密度较低且无固定结构,且只位于侵染细胞的细胞质中,常在侵入线附近,从不出现在侵染细胞的液泡内和非侵染细胞里面.

The infection threads in Onobrychis viciaefolia root nodules were studied with transmission electron microscopy. The results shown as follows. （1） the infection threads were formed by the invaginations of the intercellular spaces or intercellular layers of the host cell walls. The invaginations might occur on one side or both sides of an intercellular layer. Sometimes the invaginations even appeared at the same portion of an intercellular layer, forming two or three infection threads. The infection threads were smaller in sizes. Most of them were tube-like,a small quantity of them were pocket-shaped. The infection threads had abundant matrix, but in which only a little bacteria were. They often had more matrix regions more than one which were different in electron dense, infection thread wall thickness and bacterial number. Some regions even lacked infection thread wall or bacterium, but the surface of every infection thread was surrounded by a layer of infection thread membrane. （2）The infection threads were very abundant in the nodule cells and very wide in distribution. They were always located in the mature infected cells, besides a large quantity in meristematic cells and young infected cells. （3）In addition,the root nodules still had a kind of special structure that was approximately round and was surrounded by a layer of membrane. Its matrix was lower in electron dense and lacked fixed structure. The special structures only appeared in the infected cell, never in the meristematic cell and uninfected cell,only were located in the cytoplasm of the infected cell, never in the vacuole of the infected cell. Thev were often near the infection threads.