Colonization of the nitrogen-fixing bacterium Gluconacetobacter diazotrophicus in a large number of Canadian corn plants

Abstract

Gluconacetobacter diazotrophicus is a nitrogen-fixing bacterium originally found in sugarcane. In this report, we studied colonization of this bacterium in corn (Zea mays) using 17 inbred grain corn lines and 10 sweet corn varieties. Gluconacetobacter diazotrophicus was inoculated to roots of different corn plants. Thirty days after inoculation, the presence of the bacterium in plant tissues was evaluated via polymerase chain reaction using specific primers. The research showed that it was possible to introduce G. diazotrophicus into a large number of corn genotypes. The bacterium was detected in 11 grain corn lines and 9 sweet corn varieties and the overall colonization in corn was 74.1%. The bacterium was detected in stems and leaves from the primary site of inoculation, indicating the bacterium could move to other organs and the bacterium showed a positive adaptation to the new host plant. The bacterium population size in colonized plants ranged from 200 to 3000 per fresh gram of tissues. Some grain and sweet corn genotypes were not colonized by the bacterium, indicating that genetic difference exists in corn plants which influences colonization. Sucrose content in stem tissues of sweet corn varieties was higher than that in grain plants. Analysis of all the corn genotypes showed that there was a positive correlation between plant sucrose content and colonization efficiency. The study indicates that corn can be a potential new host plant for G. diazotrophicus.Key words: Grain corn, nitrogen-fixing bacterium, sugar content, sweet corn