WITZIG, STEPHEN B.* AND MARK A. HOLLAND. Department of Biology, Richard A. Henson School of Science and Technology, Salisbury State University, Salisbury, Maryland 21801. - A MICROBIAL SYMBIONT USED TO ALTER THE NUTRITIONAL QUALITY OF PLANTS.
PPFMs (pink-pigmented facultative methylotrophs - especially
Methylobacterium spp.) are bacterial symbionts of plants, shown
previously to participate in plant metabolism. One on-going theme of
research in our lab is the development of methods for exploiting the
relationship between these bacteria and their host plants for plant
improvement. We report here on our efforts to alter the nutritional
quality of crop plants by replacing their native PPFMs with selected
mutant strains of the bacteria. Using a combination of selective
media and auxotrophic mutants of E.coli and Arthrobacter
sp., we isolated methionine- and vitamin B12-overproducing PPFM
mutants and have colonized plants with them. Our hope is that the
PPFM overproducers will feed the host, resulting in an increase of B12
or methionine in host tissues. Analysis of these plants is in
progress. The significance of this strategy for improvement of crop
plants is discussed.
Key words: Methylobacterium, mutant selection, nutrition, PPFM, symbiosis