Recent studies on the Rhizobium-legume symbiosis

Microscopic evidence on how iron deficiency limits nodule initiation in Lupinus angustifolius L.

“…However, in of the infection threads. Bacteria are released into developing lupin nodules, infection threads have cytoplasm through a degradation of the infection been subsequently found in nodule tissue, each with thread wall or folding of host plasmamembrane wall material continuous with the cell wall of the (Nutman, 1956;Dart, 1974Dart, , 1977Dazzo, 1980;plant (Robertson eZ a/., 1978). Meijer, 1982).…”

Attachment of Rhizobiaceae to Plant Cells

“…Depending on the culture conditions, possible ligands for binding by trifoliin A are LPS, CPS and EPS oligosaccharide fragments, coming from the clover symbiont R. leguminosarum bv trifolii (R.I. trifolii) (Hrabak et ai., 1981;243 Sherwood et al, 1984b;Abe et aI., 1984). Interestingly, an R.I. trifolii mutant lacking its Sym plasmid was unable to bind trifoliin A, and showed significantly diminished attachment to clover root hairs (Dazzo et al, 1988). In contrast, a Sym plasmid-deficient R.I. viciae strain is perfectly able to attach to pea root hairs, its accumulation at root hair tips being facilitated by pea lectin.…”

“…Cellulose-deficient R. leguminosarum cells are still able to attach to the root hair surface, and do not show significant nodulation defects under laboratoty conditions (Smit et al, 1987). Several authors have obtained indications that rhizobial nod genes, involved in synthesis of LCOs, playa role in host-plant-specific attachment (Dazzo et al, 1988). These indications are based on a comparison of attachment kinetics of homologous wild type strains with those of certain nod mutants and heterologous strains.…”