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Effects of zinc on dune lupine and its microbial community
Michael Piña, Jessica Duong, Michelle Lum
Department of Biology, Loyola Marymount University, Los Angeles, California 90045
• Several of the bacterial isolates were chosen
for further characterization and identified by
16S rDNA as Bradyrhizobium, Rhizobium, or
Variovorax.
• The isolates did not nodulate L. perennis.
• Preliminary data shows that high
concentrations of zinc stresses L. chamissonis.
• In high concentrations of zinc (100µM
ZnSO₄), L. chamissonis had longer shoots and
shorter roots than those plants treated with
lower concentrations of ZnSO₄.
• Overall, plants grown in lower concentrations
of ZnSO₄ appeared healthier, with more robust
leaves and a larger root system.
• Strain LCN3-4 showed the greatest resistance
to increased zinc concentrations whereas
strains LCN1-3, LCN3-1, and LCN3-2 were
the most sensitive to zinc.
No zinc
5µM zinc
- control
+ control
LCN2-2
LCN1-3
LCN3-3
LCN3-2
LCN3-1
Figure 2.
Phylogenetic
tree of L.
chamissonis
nodule isolates.
Selected isolates
were identified
using BLAST.
25µM zinc
Figure 1. View of
Ballona Wetlands in
Los Angeles, CA
- control
+ control
LCN3-6
LCN3-2
LCN2-1
Ladder
Ladder
A
100µM zinc
Figure 4. Growth of nodule isolates on
increasing concentration of zinc. Bacterial
isolates from L. chamissonis nodules show
decreased growth as the concentration of zinc
sulfate increases, with the exception of strain
LCN3-4.
Materials and methods
• Nodules from L. chamissonis roots were
surface sterilized, crushed, bacteria isolated,
and pure cultures made of individual isolates.
• L. chamissonis and L. perennis seeds were
grown axenically and inoculated with bacterial
isolates.
• The 16S rDNA gene of selected strains were
amplified by polymerase chain reaction (PCR)
for sequencing analysis.
• Sequences were identified using BLAST to
compare to public databases and a
phylogenetic tree was generated.
• L. chamissonis and selected bacterial strains
are being grown using media with various
concentrations of zinc sulfate.
Conclusions
•Nodulators of L.chamissonis have not yet been
confirmed, though it likely one of the isolated
bacteria from the nodules.
•High concentrations of zinc appears to stress L.
chamissonis growth, causing longer shoots and
shorter roots. Zinc also appears to stress the
growth of the microbial community associated
with L. chamissonis.
•Future work will characterize how the microbial
community of L. chamissonis impacts plant
growth and how zinc impacts this association.
•Decreasing numbers of dune lupine along its
native California coast suggest that the species
does not adapt well to the effects of urbanization.
An increase of heavy metals due to urban runoff
is likely to affect the growth of these plants,
which provide ecosystem services to the nearextinct El Segundo Blue Butterfly, as well as
other local wildlife. Continuing research on L.
chamissonis and its nodulating symbiont is vital
to ongoing restoration efforts of the Ballona
wetlands.
Literature cited
LCN5-3
•Nitrogen is one of the most essential nutrients for
plant growth and development. However, plants
are unable to use nitrogen in its natural
atmospheric form. Many members of the legume
family are able to develop symbiotic relationships
with Rhizobia, which convert nitrogen to a usable
form for plants in exchange for carbohydrates.
The bacteria usually fix nitrogen for plants in
structures called nodules, which develop on roots.
•Lupinus chamissonis (dune lupine) is a known
nodulating species of the legume plant family.
However, the identification of its microbial
community remains unknown. As such, we seek
to identify the bacterial associators of dune lupine
and characterize their effect(s) on lupine
development.
•Dune lupine is found natively along the
California coast. In the Ballona wetlands and El
Segundo sand dunes near Loyola Marymount
University, there is an ongoing effort to
understand the effects of urban runoff on sand
dunes, where dune lupine grows. This study
investigates how urban stresses, such as heavy
metal contamination, can impact the partners in
the Rhizobia-legume symbiosis.
Results
Ladder
Introduction
Y. Benhizia, H. Benhizia, A. Benguedouar, et al.
Gamma proteobacteria can nodulate legumes
of the genus Hedysarum. System. Appl.
Microbiol. 27: 462-468.
A. Jarabo-Lorenzo, R. Perez-Galdona, J. DonateCorrea et al. 2003. Genetic diversity of
Bradyrhizobial populations from diverse
geographic origins that nodulate Lupinus spp.
and Ornithopus spp. Systematic and Appl.
Microbiol. 26: 611-623.
Acknowledgments
• Funding was provided by the Loyola
Marymount University Department of Biology.
• Special thanks to Elisabeth Ferris for her
assistance throughout the project.
B
C
Figure 3. PCR products of 16S rDNA visualized by
gel electrophoresis. (A,C) The positive control used
was Burkholderia tuberum gDNA. The negative
control used was water. (A,B,C) Red arrows denote
band length of interest.
For further information
Figure 5. Lupinus chamissonis grown in media
containing zinc sulfate.
Please contact [email protected] or
[email protected]. More information on this
and related projects can be obtained at
www.teamlum.com. A PDF-version of the poster
is also available.