Adherence of Agrobacteria to Moss Protonema and Gametophores Viewed by Scanning Electron Microscopy

Abstract

The attachment of certain Agrobacterium species to moss protonema was examined by scanning electron microscopy. The bacteria cultured with the moss adhered to the protonemal filaments of Pylaisiella selwynii and Funaria hygrometrica throughout the fixation and washing procedure prior to examination. The number of bacteria adhering per unit length of filament did not correlate with the ability of four species (A. tumefaciens, A. rubi, A. rhizogenes, A. radiobacter) to induce gametophore formation in P. selwynii. Little difference was found between the number of A. tumefaciens on P. selwynii or on F. hygrometrica, and although this bacterial species induced gametophores on P. selwynii, it had no effect on F. hygrometrica. A. rhizogenes, which is capable of inducing rhizoid formation on both P. selwynii and F. hygrometrica without physical attachment, did associate with filaments of both mosses. Larger numbers of A. tumefaciens and A. rubi, which induce gametophores or callus, were associated with the spore and germ tube of P. selwynii than were A. rhizogenes or A. radiobacter which do not initiate these changes. These results suggest that the germ tube may constitute the site where effective attachment occurs. The number of A. tumefaciens adhering to P. selwynii was greatest at 2–6 h after addition and then decreased by 26 h, raising the possibility that some bacteria lyse following attachment. None of the bacteria adhered to the gametophore walls of either moss, indicating that a change in cell wall surface may occur. The four species of Agrobacterium differed in their orientation when adhering to the moss. These results suggest that the process of bacterial adherence to higher plant cells in Agrobacterium infection is similar to that which we observe in mosses and which leads to developmental changes.

In Vitro Binding of Agrobacterium tumefaciens to Plant Cells from Suspension Culture

“…There are few reports on the influence of these compounds on tumor induction in vivo (19), although A. tumefaciens was found to contain a relatively large amount of phosphatidylcholine in their cell envelopes (23). Polycations such as poly-L-ornithine, poly-L-lysine, and DEAE-dextran are known to increase greatly the uptake of plant virus (32), its RNA (2), and DNA (28) (31). The mechanism of binding of A. tumefaciens to cell walls of plants is unknown at present.…”

Moss Growth and Development is Facilitated by Natural Bacterial Flora

“…Inoue et al (1980) also found d\fferences between juvenile and mature cell walls of mosses. Such differences may account for the fact that agrobacteria associate with the cell walls of protonema but not gametophores (Spiess et al 1977b). …”

“…tumefaciens which are tumorigenic on higher plants, while strains which are non-infectious (e.g., A. radiocter) are less effective (Spiess et al 1977a(Spiess et al , 1977b(Spiess et al , 1981a. ~.…”

Agrobacterium rhizogenes: paving the road to research and breeding for woody plants

“…A. rhizogenes is a Gram-negative bacterium, which contains the root-inducing (Ri) plasmid that induces plants to produce hairy roots from wounds (Moore et al, 1979;White and Nester, 1980a;Chilton et al, 1982;Lothar et al, 1982). Currently, a wide range of plant species, including angiosperms (both dicotyledonous and monocotyledonous plants), gymnosperms, and even moss, have been found to be susceptible to successful infection by A. rhizogenes (De Cleene and De Ley, 1981;Porter and Flores, 1991;Spiess et al, 1977;Masako et al, 2004). The T-DNA fragment on the Ri plasmid integrates into the host plant genome, causing hairy root formation.…”