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Intraspecific variation in thermal acclimation of photosynthesis across a range of temperatures in a perennial crop

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ABSTRACT

Plants acclimate to the thermal regime they experience. We analysed intra-specific variations in the thermal acclimation of photosynthesis in a perennial herbaceous crop by comparing cultivars from contrasting origins grown at a range of temperatures. It was concluded that both temperate and Mediterranean cultivars display strong patterns of thermal acclimation in the 5-40°C range. No evidence of superior performance was found for Mediterranean genotypes at high temperatures.

No MeSH data available.


Predicted responses to leaf temperature of the RuBP carboxylation limited (full line, Ac) and the RuBP regeneration limited (dotted line, Ar) assimilation rates at 400 ppm CO2 and growth temperatures of 5 °C (a–g), 10 °C (b–h), 20 °C (c–i), 25 °C (d–j), 30 °C (e–k) and 35 °C (f–l). Data are for two alfalfa genotypes of temperate (a–l, G3) and Mediterranean (g–l, 7_7) origins. Arrows indicate the predicted thermal optimum Heat-bleached leaves (l) were unsuitable to derive Vcmax and Jmax parameters from gas exchange measurements, and therefore no Ac and Ar curves were simulated.
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plw035-F6: Predicted responses to leaf temperature of the RuBP carboxylation limited (full line, Ac) and the RuBP regeneration limited (dotted line, Ar) assimilation rates at 400 ppm CO2 and growth temperatures of 5 °C (a–g), 10 °C (b–h), 20 °C (c–i), 25 °C (d–j), 30 °C (e–k) and 35 °C (f–l). Data are for two alfalfa genotypes of temperate (a–l, G3) and Mediterranean (g–l, 7_7) origins. Arrows indicate the predicted thermal optimum Heat-bleached leaves (l) were unsuitable to derive Vcmax and Jmax parameters from gas exchange measurements, and therefore no Ac and Ar curves were simulated.

Mentions: The photosynthetic parameters and their responses to leaf temperature [Supporting Information Table 1] were used as inputs for the Farquhar model in order to investigate their respective roles in the acclimation of photosynthesis to Tgrowth. When the whole set of measured parameters was applied, the model proved able to account for the changes in A400 observed both within (i.e. different Tleaf) and between Tgrowth (RMSE < 2 µmol m−2 s−1, no significant bias; [Supporting Information Figure 2]). In the two genotypes, the relationship between observed and predicted A400 values did not differ from the 1:1 line (t-value < 1.07, P > 0.3 for the intercept; t-value > 32.0, P < 10−3 for a slope equal to 0.95 ± 0.05). The limiting steps of photosynthesis associated with these simulations are presented in Figure 6. As expected from the response curves of the Vcmax and Jmax parameters, the temperature dependencies of the assimilation rates limited by RuBP carboxylation (Ac) and RuBP regeneration (Ar) differed at all growth temperatures. In both temperate and Mediterranean genotypes, the optimal temperature predicted by the model (arrows, Fig. 6) increased with rising Tgrowth and was closely related to observed Topt[Supporting Information Figure 6]. Except at 5 °C, Topt was determined by the intersection of A400,c and A400,r in all the situations studied. At Topt, photosynthesis was thus generally co-limited by RuBP carboxylation and RuBP regeneration. At 5 °C however, A400,r was higher than A400,c irrespective of leaf temperature (about 1.5-fold), and RuBP carboxylation systematically appeared as the limiting step. Outside the optimal temperature range, the limiting step of photosynthesis also changed as a function of Tgrowth. Under cold growing conditions (i.e. below 10 °C), A400,c fully explained the temperature dependency. In contrast, at warmer Tgrowth, A400,c generally appeared to be the limiting step above Topt, whereas A400,r limited assimilation below Topt.Figure 6.


Intraspecific variation in thermal acclimation of photosynthesis across a range of temperatures in a perennial crop
Predicted responses to leaf temperature of the RuBP carboxylation limited (full line, Ac) and the RuBP regeneration limited (dotted line, Ar) assimilation rates at 400 ppm CO2 and growth temperatures of 5 °C (a–g), 10 °C (b–h), 20 °C (c–i), 25 °C (d–j), 30 °C (e–k) and 35 °C (f–l). Data are for two alfalfa genotypes of temperate (a–l, G3) and Mediterranean (g–l, 7_7) origins. Arrows indicate the predicted thermal optimum Heat-bleached leaves (l) were unsuitable to derive Vcmax and Jmax parameters from gas exchange measurements, and therefore no Ac and Ar curves were simulated.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4940478&req=5

plw035-F6: Predicted responses to leaf temperature of the RuBP carboxylation limited (full line, Ac) and the RuBP regeneration limited (dotted line, Ar) assimilation rates at 400 ppm CO2 and growth temperatures of 5 °C (a–g), 10 °C (b–h), 20 °C (c–i), 25 °C (d–j), 30 °C (e–k) and 35 °C (f–l). Data are for two alfalfa genotypes of temperate (a–l, G3) and Mediterranean (g–l, 7_7) origins. Arrows indicate the predicted thermal optimum Heat-bleached leaves (l) were unsuitable to derive Vcmax and Jmax parameters from gas exchange measurements, and therefore no Ac and Ar curves were simulated.
Mentions: The photosynthetic parameters and their responses to leaf temperature [Supporting Information Table 1] were used as inputs for the Farquhar model in order to investigate their respective roles in the acclimation of photosynthesis to Tgrowth. When the whole set of measured parameters was applied, the model proved able to account for the changes in A400 observed both within (i.e. different Tleaf) and between Tgrowth (RMSE < 2 µmol m−2 s−1, no significant bias; [Supporting Information Figure 2]). In the two genotypes, the relationship between observed and predicted A400 values did not differ from the 1:1 line (t-value < 1.07, P > 0.3 for the intercept; t-value > 32.0, P < 10−3 for a slope equal to 0.95 ± 0.05). The limiting steps of photosynthesis associated with these simulations are presented in Figure 6. As expected from the response curves of the Vcmax and Jmax parameters, the temperature dependencies of the assimilation rates limited by RuBP carboxylation (Ac) and RuBP regeneration (Ar) differed at all growth temperatures. In both temperate and Mediterranean genotypes, the optimal temperature predicted by the model (arrows, Fig. 6) increased with rising Tgrowth and was closely related to observed Topt[Supporting Information Figure 6]. Except at 5 °C, Topt was determined by the intersection of A400,c and A400,r in all the situations studied. At Topt, photosynthesis was thus generally co-limited by RuBP carboxylation and RuBP regeneration. At 5 °C however, A400,r was higher than A400,c irrespective of leaf temperature (about 1.5-fold), and RuBP carboxylation systematically appeared as the limiting step. Outside the optimal temperature range, the limiting step of photosynthesis also changed as a function of Tgrowth. Under cold growing conditions (i.e. below 10 °C), A400,c fully explained the temperature dependency. In contrast, at warmer Tgrowth, A400,c generally appeared to be the limiting step above Topt, whereas A400,r limited assimilation below Topt.Figure 6.

View Article: PubMed Central - PubMed

ABSTRACT

Plants acclimate to the thermal regime they experience. We analysed intra-specific variations in the thermal acclimation of photosynthesis in a perennial herbaceous crop by comparing cultivars from contrasting origins grown at a range of temperatures. It was concluded that both temperate and Mediterranean cultivars display strong patterns of thermal acclimation in the 5-40&deg;C range. No evidence of superior performance was found for Mediterranean genotypes at high temperatures.

No MeSH data available.