Abstract: Structural analysis of nodule-like tissues on rice roots collected from Wenzhou District of Zhejiang Province were conducted by using LM, SEM and TEM, and compared with that of nodules on leguminous plants. The observation showed the followings: During the stage of young rice shoots the bacteria were distributed in either dispersed or aggregated form in a few of the host cells of the nodule-like tissue, but the host cells showed their defence reaction to the bacteria, resulting in cytoplasmic agglutination and fibrillation, from which the fine structure of cytoplasm became undistinguishable, indicating the death of infected cells; during the booting or earing stage of rice, the surfaces of the nodule-like tissues were dark-brown with phellem matrial. In the exo-cortex there were no vascular tissue. In the endo-cortex the parenchyma cells were expanded and no bacteria were observed. In some of the nodule-like tissues the exo-and endo-cortical cells were basically lignified. It was clearly shown that there were gear wheel-like structures especially existing in the endo-cortical cells. Under the observations by LM, SEM, these structures were identified as coral-like balls of fibre-like material. In fact, they are spores of a kind of fungi with hyphae. Therefore, the nodule-like tissues on rice roots collected from Wenzhou District of Zhejiang Province are completely different from the genuine nodules on leguminous roots. In fact, they are calluses infected by bacteria and fungi.

Key words: Rice, Nodule-like tissue, Nodule, Legumes, Fungus