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Interactive Effects of Elevated CO 2 and Growth Temperature on the Tolerance of Photosynthesis to Acute Heat Stress in C 3 and C 4 Species
Author(s) -
Hamilton III E. William,
Heckathorn Scott A.,
Joshi Puneet,
Wang Dan,
Barua Deepak
Publication year - 2008
Publication title -
journal of integrative plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.734
H-Index - 83
eISSN - 1744-7909
pISSN - 1672-9072
DOI - 10.1111/j.1744-7909.2008.00747.x
Subject(s) - photosynthesis , stomatal conductance , thermolabile , acclimatization , photosystem ii , biology , heat stress , chlorophyll fluorescence , photosynthetic capacity , carbon dioxide , horticulture , botany , chemistry , zoology , ecology , biochemistry , enzyme
Determining effects of elevated CO 2 on the tolerance of photosynthesis to acute heat‐stress (heat wave) is necessary for predicting plant responses to global warming, as photosynthesis is thermolabile and acute heat‐stress and atmospheric CO 2 will increase in the future. Few studies have examined this, and past results are variable, which may be due to methodological variation. To address this, we grew two C 3 and two C 4 species at current or elevated CO 2 and three different growth temperatures (GT). We assessed photosynthetic thermotolerance in both unacclimated (basal tolerance) and pre‐heat‐stressed (preHS = acclimated) plants. In C 3 species, basal thermotolerance of net photosynthesis (P n ) was increased in high CO 2 , but in C 4 species, P n thermotlerance was decreased by high CO 2 (except Zea mays at low GT); CO 2 effects in preHS plants were mostly small or absent, though high CO 2 was detrimental in one C 3 and one C 4 species at warmer GT. Though high CO 2 generally decreased stomatal conductance, decreases in P n during heat stress were mostly due to non‐stomatal effects. Photosystem II (PSII) efficiency was often decreased by high CO 2 during heat stress, especially at high GT; CO 2 effects on post‐PSII electron transport were variable. Thus, high CO 2 often affected photosynthetic theromotolerance, and the effects varied with photosynthetic pathway, growth temperature, and acclimation state. Most importantly, in heat‐stressed plants at normal or warmer growth temperatures, high CO 2 may often decrease, or not benefit as expected, tolerance of photosynthesis to acute heat stress. Therefore, interactive effects of elevated CO 2 and warmer growth temperatures on acute heat tolerance may contribute to future changes in plant productivity, distribution, and diversity.