Perception of Rhizobium nodulation factors by tomato cells and inactivation by root chitinases.

Abstract

The bacterial genera Rhizobium and

Expression of the early nodulin, ENOD40, in soybean roots in response to various lipo‐chitin signal molecules

“…Chitin oligomers, the backbone of the nod signals, are known as potent elicitors in some cultured cell systems such as tomato (Felix et al, 1993) or rice (Yamada et al, 1993). Indeed, known chitin oligomer elicitors, as well as purified or crude preparations of Rhizobium and B. japonicum nod signals, provoked a rapid alkalinization of culture medium when applied to suspension-cultured tomato cells (Staehelin et al, 1994). This is an effect generally attributed to elicitors of plant defense reactions.…”

Study of the Intercellular Fluid of Healthy Lupinus albus Organs (Presence of a Chitinase and a Thaumatin-Like Protein)

“…Additionally, recent data indicate a further possible role for chitinases constitutively present in legume roots, i.e. the hydrolysis and inactivation of nodulation-inducing factors contributing to the host specificity of rhizobia (Staehelin et al, 1994).…”

Plant defence genes are induced in the pathogenic interaction between bean roots and Fusarium solani, but not in the symbiotic interaction with the arbuscular mycorrhizal fungus Glomus mosseae

“…This would not have been expected if mycorrhizal fungi produced general suppressors of defence. Rhizobia, symbiotic bacteria of legume roots, also do not elicit plant defence responses when infecting roots, except for certain plant responses that might be important for the regulation of nodulation (Vasse, de Billy & Truchet, 1993 ;Staehelin et al, 1994). In the Rhizobium legume symbiosis, bacterial mutants lacking certain exopolysaccharides have been described that behaved like pathogens when infecting roots (Niehaus, Kapp & Pu$ hler, 1993 ;Parniske et al, 1994).…”