Page 219 - PC2019 Program & Proceedings

PLANT CANADA 2019

P11. Addition of sulfur decreases total cadmium uptake but increases cadmium translocation in
soybean
Matt, S.; P. Boersma; Macfie, S.
University of Western Ontario

Cadmium (Cd) is a toxic metal that is increasing in concentration in agricultural soil due to anthropogenic
activity (e.g., industrial waste, impure fertilizers). Contaminated crops could pose a potential health risk
for consumers. Many studies have reported the positive effects of exogenous sulfur (S) in reducing Cd
uptake and translocation in rice (Oryza sativa). However, the extent to which this phenomenon applies to
other crop species is unknown. Soybean (Glycine max) seedlings were grown hydroponically in a full
factorial design with 0 or 20 uM CdCl2 and 0, 2.5, or 5 mM Na2SO3. The total amount of Cd taken up
decreased from 72.5 ± 0.1 ug per plant (no S added) to 18.9 ± 0.04 ug per plant (5 mM S added) despite
the S-induced 10-15% increase in bioavailable Cd in solution. Within S-treated root cross sections, more
Cd was localized at the exodermis, less Cd was in the stele, and Casparian bands were visibly thicker.
These patterns suggest reduced opportunity for Cd to enter the xylem and to be translocated aboveground.
However, proportionately more of the internal Cd was translocated to the shoots (31% of total Cd with no
S added; 88% of total Cd with 2.5 and 5 mM S added). Soybean is therefore an unsuitable crop for
growth on Cd-contaminated soils treated with exogenous S.

Sheila Macfie (smacfie@uwo.ca)

P12. Impacts of root-associated fungi on tree growth under elevated temperature and CO2
1
2
3
*1
Frank, J. ; D. Way ; T. Ramsfield ; M. Abou-Zaid
2
( Western University; University of Western Ontario; National Resources Canada)
1
3
Growth of poplars, an economically important group of trees, has been declining due to elevated
temperatures and droughts associated with climate change. Symbiotic microbes, such as root-associated
fungi (RAF) may increase plant growth under climate change conditions, by altering tree metabolic
profiles and increasing tree access to water and nutrients. To address this hypothesis, three RAF were
isolated from poplar roots in the field. We then determined the effects of RAF inoculation on poplar
growth under a range of future climate scenarios: ambient (400 ppm) or elevated CO2 (750 ppm) with
either ambient temperatures, or a +4 ˚C or +8˚C warming treatment. Colonization of poplar roots by RAF
increased with elevated temperature and CO2 with some RAF having up to a 336% increase. Inoculation
with RAF did not increase plant height or total dry weight in plants grown at ambient CO2. However,
inoculated trees grown under +4 °C with elevated CO2 were taller and had greater biomass than trees
from ambient CO2 treatments with either ambient or +4 °C temperatures. Non-inoculated trees also had a
significant increase in biomass when grown at higher CO2 and temperature conditions, although this CO2
effect was reduced in the +8 °C treatment. Our results suggest that RAF increases tree growth under
moderate warming (+4 °C) and may provide resilience to future climatic stresses.

Joshua Frank (jfrank22@uwo.ca)

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