[Microstructure of pea nodules infected with a neomycin-resistant mutant of nodule bacteria]

The neomycin-resistance mutation of pea nodule bacteria does not interfere with the formation of infection threads when the bacterium inoculates the host plant, or with the axial differentiation of the nodular tissue. At the same time, intracellular neomycin-resistant nodule bacteria do not acquire the bacteroid structure. Once the bacterium is incorporated into the cytoplasm of the host cell, it loses the peribacteroid membrane and undergoes lysis. Therefore, the neomycin-resistant pea nodule bacterium realizes the initial infection stage (including the formation of infection threads), but is defective in the subsequent stages. Hence, the described stages of plant infection are determined by independent properties of the bacterium.