Technical approaches to inoculate micropropagated sugar cane plants were Acetobacter diazotrophicus

Micropropagated plantlets of sugar cane were inoculated with the N-2-fixing bacterium Acetobacter diazotrophicus. Various modifications on the basic p lant culture medium MS were made for the plant/bacteria association. The pr otocol required the inoculation of the bacteria at the end of the rooting p eriod in a medium without hormones or vitamins, and with the concentration of sugar and mineral nutrients reduced by a factor of 10. Individual plants were inoculated with A. diazotrophicus and maintained under the appropriat e light and temperature condition used for micropropagation up to 7 days. T he system favored the infection and the establishment of the bacteria withi n the plant tissue. Bacteria colonized the plant tissue and accumulated in inter-cellular cavities and the region of lateral root emergence and also c olonizes the xylem vessels. The inoculated plantlets were subsequently tran sferred to the acclimatization phase and after 30 days it was possible to i solate the bacteria from plant tissue. This protocol permitted studies of i nfection and comparison among strains.