Zhang, H., Pan, C., Gu, S.,
Ma, Q., Zhang, Y., Li, X.
and Shi, K.
2019
Stomatal movements
are involved in elevated CO2
-mitigated high temperature
stress in tomato.
Physiologia Plantarum
165: 569-583.
NOTE:
The extreme
weather events,
such as heat waves,
have not increased
during the mild
global warming
in the past
100 years.
Will higher levels of CO2
make heat waves worse
for plants in the future ?
Seven Chinese researchers
studied the interactive effects
of elevated CO2 and a simulated
heat wave on tomato seedlings
(Solanum lycopersicum, cv. Ailsa Craig)
SUMMARY:
Following two days of heat shock,
the ambient CO2-treated plants
were severely wilted.
Yet plants in the elevated CO2
treatment had only just begun
to wilt.
Further evidence
of heat stress mitigation
by CO2 is presented
is in Figure 1,
which shows --
in the authors' words
-- that:
"elevated CO2
significantly alleviated
the heat stress-related
increase in relative
electrical conductivity
and decrease in leaf
photochemical
quantum yield
of photosystem II
(ΦPSII)
values by 52%
and 25%,
respectively."
Elevated CO2
impacted genes
associated with
hydrogen peroxide
(H2O2)
accumulation,
that helped
decrease
stomatal
aperture,
which ultimately
"played a
crucial role
in elevated
CO2-induced
heat tolerance
by maintaining
a balance
between
water retention
and heat loss."
Zhang et al. report
their findings are
"consistent with
previous studies
that describe
how CO2 enrichment
improves plant tolerance
to various unfavorable
conditions:
(Taub et al., 2000;
Qaderi et al., 2006;
Xu et al., 2013;
Yu et al., 2014)."
Researchers
subjected
tomato plants
at the five-to-six
leaf stage to one
of two CO2
treatments
( 400 or 800 ppm )
in controlled
environment
chambers.
After two days
of CO2 treatment,
they exposed half
of the plants, in each
CO2 concentration,
to 48 hours
of heat stress
(+17°C above the control
treatment of 25°C).
Chart Below:
(Panel A)
Representative chlorophyll fluorescence images of the leaf photochemical quantum yield of photosystem II (ΦPSII) after 24 h of heat stress treatment (+17°C above control) of tomato seedlings under ambient (400 ppm) or elevated (800 ppm) CO2 (eCO2). The color gradient scale at the top of the image indicates the magnitude of the fluorescence signal.
(Panel B)
Leaf average ΦPSII values after 24 h of heat stress treatment under ambient or eCO2 as in Panel A. The results are presented as the means ± SD. Different letters indicate significant differences between treatments (P < 0.05) according to Tukey's test. Source: Zhang et al. (2019).
References
Qaderi, M.M., Kurepin, L.V. and Reid, D.M. 2006. Growth and physiological responses of canola (Brassica napus) to three components of global climate change: temperature, carbon dioxide and drought. Physiologia Plantarum 128: 710-721.
Taub, D.R., Seemann, J.R. and Coleman, J.S. 2000. Growth in elevated CO2 protects photosynthesis against high-temperature damage. Plant, Cell and Environment 23: 649-656.
Xu, Z., Shimizu, H., Yagasaki, Y., Ito, S., Zheng, Y. and Zhou, G. 2013. Interactive effects of elevated CO2, drought, and warming on plants. Journal of Plant Growth Regulation 32: 692-707.
Yu, J., Yang, Z., Jespersen, D. and Huang, B. 2014. Photosynthesis and protein metabolism associated with elevated CO2-mitigation of heat stress damages in tall fescue. Environmental and Experimental Botany 99: 75-85.