XVI International Botanical Congess

Lupin plants infected with nol L and nod Z strains of Rhizobium showed delayed nodulation and nitrogen deficiency. Both mutations caused identical defects in root nodule morphogenesis. In 10-day old nodules changes in bacteroid tissue ultrastructure were most evident. Bacteroidal cells contained symbiosomes associated with clusters of membrane-surrounded vesicles filled with fine-fibrillar matrix. Many vesicles contained bacteria within matrix. Sometimes the structures invaded phragmoplast during mitosis resulting in erroneous cell plate formation and cell-wall discontinuity, which suggests incorrect interaction between cytoskeleton of host-cell and membrane, which surrounds bacteria.