Bacteria Isolated from Moss and Their Effect on Moss Development

Bacteria from four species of mosses from different geographical locations were isolated either on media selective for agrobacteria or on nutrient broth. Many isolates induced developmental changes in Pylaisiella selwynii protonemal filaments comparable to those obtained with agrobacteria. No bacteria induced crown gall or hairy root symptoms on beans, tomato, or Kalanchoe, although a few promoted callus growth on potato tuber and also promoted callus and roots on carrot disks, similar to Agrobacterium rhizogenes. Many isolates bind to specific Agrobacterium attachment sites in wounds; five of seven tested isolates competed with virulent Agrobacterium tumefaciens for these sites on bean leaves. No isolate could unequivocally be assigned to the genus Agrobacterium by several physiological and biochemical tests used to classify Agrobacterium. These results demonstrate that bacteria adhering to moss in nature may affect protonemal growth and gametophore initiation and thus may be an important ecological factor in regulating normal life cycle events at this stage of moss development.