Abstract Detail

Symbioses: Plant, Animal, and Microbe Interactions

Pec, Gregory [1], Breight, Michael [2], Johnson, Shaylee [2], Twigg, Paul [1], Shaffer, Julie [1].

Response of soil bacterial communities to redroot pigweed (Amaranthus retroflexus) invasion in corn (Zea mays).

Globally important crop species such as corn (Zea mays) are commonly limited by water deficit stress, nitrogen availability and weed interference. Of these, weedy plant species compete with corn for water, light, and nutrient availability, with uncontrolled weeds being a major constraint to corn production. Among the most aggressive weed species in terms of growth in corn fields is redroot pigweed (Amaranthus retroflexus). A small-seeded broadleaf summer annual, redroot pigweed is characterized by prolific seed production, herbicide resistance and allelopathic effects, with the latter hypothesized to cause changes in soil bacterial community structure in favor of invasion success. Here, we examined the influence of redroot pigweed on soil bacterial community composition and diversity. As less is understood about individual ecological roles within the highly diverse bacterial domain, we expected a range of responses within the soil bacterial community. Additionally, as changes in soil bacterial diversity may be associated with changes across the growing season, a secondary objective was to examine any seasonal responses in soil bacterial diversity and composition. We chose two sites, one representative of redroot pigweed invasion and another representative of corn yield for the state of Nebraska. Within each site, plots were established and redroot pigweed was allowed to germinate and grow from the seed bank present in those soils; whereas, corn (B73) was planted. Soil samples were collected in both pigweed and corn plots across the growing season and processed to characterize the soil bacterial community via 16S high-throughput sequencing. Overall, there was a one-fold increase in bacterial diversity in pigweed-invaded versus corn soils. Across the growing season, bacterial diversity within corn-dominated soils remained invariant, whereas bacterial diversity within pigweed-invaded soils increased by twenty percent. Bacterial communities within pigweed-invaded soils were less dissimilar throughout the growing season than bacterial communities found in corn-dominated soils. Furthermore, only six percent of bacterial taxa were common in both pigweed and corn soils. Surprisingly, sixty-nine percent of bacterial taxa were representative of pigweed-invaded soils in contrast to only eighteen percent for corn-dominate soils. Taken together, increased bacterial diversity and strong compositional shifts were found in redroot pigweed-invaded versus corn soils.

1 - University Of Nebraska At Kearney, Department Of Biology, Bruner Hall Of Science, Rm. 335, Kearney, NE, 68849, United States
2 - University of Nebraska at Kearney, Department of Biology, Bruner Hall of Science, Rm. 335, Kearney, NE, 68849, USA

Keywords:
invasion
bacteria
Zea mays
Amaranthus retroflexus
diversity.

Presentation Type: Oral Paper
Session: SYMB1, Symbioses: Plant, Animal and Microbe Interactions 1
Location: /
Date: Monday, July 19th, 2021
Time: 1:45 PM(EDT)
Number: SYMB1006
Abstract ID:321
Candidate for Awards:None