INTERACTION OF RHIZOBACTERIA WITH LEAFY SPURGE (EUPHORBIA-ESULA L) CALLUS-TISSUE CELLS

The interaction of two rhizobacterial isolates,Pseudomonas fluorescens isolate LS102 and Flavobacterium balustinum isolate LS105, with leafy spurge cells at the cellular level was studied using scanning and ele ctron microscopy. Leafy spurge callus tissue inoculated with either is olate showed considerable changes compared to non-inoculated tissue. T he attachment of rhizobacteria to cell surfaces was associated with th e elaboration of fibrillar material which may anchor bacteria to surfa ces and contribute to mediation of the phytotoxic effect caused by rhi zobacteria. At the ultracellular level, inoculated callus tissue showe d numerous cell alterations including vesiculation and convolution of the plasmalemma, cell wall degradation and disorganization of the cyto plasm, similar to those detected in the whole plant. It is concluded t hat callus tissue may provide an excellent working model to investigat e the mode and/or mechanism of action of potential biocontrol agents o n their host plants.