CENTENNIAL HONORS COLLEGE
Western Illinois University
Undergraduate Research Day 2015
Poster Presentation
Potential of Rhizobium and Bradyrhizobium species as plant growth promoting
rhizobacteria on non-leguminous plants: Effects on corn
Dung Nguyen
Faculty Advisor: Sue Hum-Musser
Biology
Biofertilizers are innovatively new and are becoming more prominent in agriculture. The inoculants
contain Rhizobium and Bradyrhizobium which are nitrogen-fixing bacteria that form symbiotic
relationships with plants, such as legumes, and enhance the growth of plant roots, promote beneficial
plant-microbe morphology, and control pathogenic organisms. However, most studies have focused on
plants in the legume family. In this project the effect of biofertilizers on corn seed germination, growth
rate, and disease- and insect-resistance will be examined. It is hypothesized that the soil inoculants will
increase the growth rates, and may also affect disease- and insect resistance of the corn plants. Sterilized
corn seeds were inoculated with the Guard-N biofertilizer and the germination rate and root lengths were
measured. There was some difference in the germination rate and seedling root growth in the treated
group compared to the control group. The seedlings were then transferred to pots and are further treated
with inoculants. Disease resistance will be measured using the count of tissue necrotic lesions on the
leaves after exposure to a maize virus. The insect resistance will be measured using the amount of leaf
consumed by corn earworm caterpillars, Helicoverpa zea. We will also examine the gene expression of
several defense genes by observing which enzymes are being turned on or off in response to pathogens or
insects. This research would allow us to determine the effects of these inoculants on the growth rates of
plants (other than legumes) and the defensive responses against insects and pathogenic organisms.