Search

Explants of genetic tumors, tumors initiated by Agrobacterium tumefaciens strains B-6 and T-37, and excised pith plugs from Nicotiana glauca, N. langsdorffii, and N. glauca-langsdorffii were cultured on Murashige and Skoog medium. All cultures, pith callus and tumors with the exception of N. langsdorffii pith grew on this medium. Addition of glutamine to the medium resulted in highly organoid growth in N. langsdorffii pith. In order to have material comparable to other pith cultures, N. langsdorffii was initiated on 2,4-dichlorophenoxyacetic acid medium, after which it grows on complete medium as amorphous pith callus. Except for the initiation of N. langsdorffii (and N. glauca) pith, the 2,4-dichlorophenoxyacetic acid medium, caused bleaching in cultures of T-37 induced tumors and death of B-6 induced tumors. Tumor cultures, except for the seedling tumor, grew well on a minimal medium lacking kinetin, indoleacetic acid, vitamins, glycine, and inositol. Glycine was necessary only in the growth of N. langsdorffii pith callus. A tissue culture model is presented which permits comparison of the various tissue types.

Agrobacterium tumefaciens B-6 and T-37 strains, inoculated into Nicotiana glauca, N. langsdorffii, and their interspecific hybrid, which forms genetic (spontaneous) tumors as well, initiate amorphous tumors from the B-6 strain and organoid tumors (aberrant roots, stems, and buds) from the T-37 strain. In the hybrid, the critical point was to induce crown gall tumors at the site of wounding and not spontaneous genetic tumors. To succeed, this inoculation had to be made at a very early (5-6 leaf stage of development). It is observed that genetic organoid tumors readily formed at the nodes following flowering or leaf abscission. Furthermore, it was noted that genetic tumor derivatives are obtainable from hybrid pith callus or hybrid seedlings cultured in vitro.A marked difference in stem elongation was observed in hybrid tobacco plants inoculated with different strains of Agrobacterium tumefaciens or distilled water, and uninoculated controls. Inoculation of hybrid plants with the B-6-G2 avirulent strain of Agrobacterium tumefaciens stimulated stem elongation over controls, the T-37 inoculated stems were slightly stunted, and the B-6 inoculated stems were quite stunted and succumbed at an early age.