Associative Nitrogen Fixation by Klebsiella spp.: Adhesion Sites and Inoculation Effects on Grass Roots

Adhesion sites on grass roots for Klebsiella strains carrying type 3 or type 1 fimbriae or both were determined. Adhesion of the strains to the roots of Poa pratensis and Festuca rubra was highly localized; the bacteria adhered strongly to root hairs and with a markedly lower efficiency to the surface of the zone of elongation and to the root cap mucilage. No adhesion to the epidermal cells between root hairs was observed. The adhesion sites were identical for the type 3- and 1-fimbriated bacteria and for P. pratensis, F. rubra, and Trifolium pratense. Inoculation of P. pratensis seedlings with Klebsiella pneumoniae strain As resulted in morphological changes in plant roots. The roots of infected plants were heavily covered with root hairs, which often were deformed and branched.     

Two β-tubulin genes,TUB1 and TUB8, of Arabidopsis exhibit largely nonoverlapping patterns of expression

Chimeric reporter genes were used to investigate the patterns of expression of two -tubulin genes, TUB1 and TUB8, in Arabidopsis thaliana. The TUB1 chimeric gene was preferentially expressed in epidermal and cortical cells of primary roots, whereas the TUB8 chimeric gene was preferentially expressed in the endodermal and phloem cells of primary roots and in the vascular tissues of leaves, stems, and flowers of transgenic plants.     

Fucose in the surface deposits of axenic and field grown roots ofZea mays L.

Summary The location of materials containing terminal fucose residues on the surface of axenic and field grown roots of corn has been determined.Binding patterns of FITC-labelled,Lotus purpureus Moench lectin indicate the presence of the fucose residues in the cell walls and mucilage of the peripheral region of the root cap. During development, fucose residues also appear in the outer periclinal walls and overlying mucilage of columnar epidermal cells. Surface material rich in these residues persists between the mature root hairs but is not found on their surface. Fucose-rich mucilage is present on the exposed surface of aerial roots and at the point where they enter the soil. No lectin binding residues are indicated elsewhere in the roots.     

The rhizosphere in Zea: new insight into its structure and development

Some of the nodal roots of field-grown Zea mays L. bear a persistent soil sheath along their entire length underground except for a glistening white soil-free zone which extends approximately 25 mm behind the root cap. These roots are generally unbranched. The histology of the surface and the rhizosphere of the sheathed roots has been examined by correlated light and electron microscopy. All mature peripheral tissues including root hairs, are largely intact and apparently alive where enclosed by the soil sheath. The sheath is permeated by extracellular mucilage which is histochemically distinct from the mucilage at the epidermal surface, but similar to that produced by the root cap. Isolated cells resembling those sloughed from the sides of the root cap persist in the soil sheath along the length of these roots. Fresh whole mounts of the sheath show that these detached cells may be alive and streaming vigorously even at some distance from the root cap. Rhizosphere mucilage is associated with the isolated cells.To whom correspondence should be addressed