David S. Kubien

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We review the current understanding of the temperature responses of C(3) and C(4) photosynthesis across thermal ranges that do not harm the photosynthetic apparatus. In C(3) species, photosynthesis is classically considered to be limited by the capacities of ribulose 1.5-bisphosphate carboxylase/oxygenase (Rubisco), ribulose bisphosphate (RuBP) regeneration(More)
C(4) plants have been reported to have Rubiscos with higher maximum carboxylation rates (kcat(CO(2))) and Michaelis-Menten constants (K(m)) for CO(2) (K(c)) than the enzyme from C(3) species, but variation in other kinetic parameters between the two photosynthetic pathways has not been extensively examined. The CO(2)/O(2) specificity (S(C/O)), kcat(CO(2)),(More)
C(4) plants are rare in the cool climates characteristic of high latitudes and elevations, but the reasons for this are unclear. We tested the hypothesis that CO(2) fixation by Rubisco is the rate-limiting step during C(4) photosynthesis at cool temperatures. We measured photosynthesis and chlorophyll fluorescence from 6 degrees C to 40 degrees C, and in(More)
Logistic problems of large-scale reforestation necessitate freezer-storage of conifer seedlings. Frozen stock is typically thawed slowly at low temperatures for up to several weeks before shipping to the plantation site, but the necessity of this practice is questionable. Experiments were conducted to study effects of different thawing regimes on(More)
Global warming and the rise in atmospheric CO(2) will increase the operating temperature of leaves in coming decades, often well above the thermal optimum for photosynthesis. Presently, there is controversy over the limiting processes controlling photosynthesis at elevated temperature. Leading models propose that the reduction in photosynthesis at elevated(More)
Rubisco, the primary photosynthetic carboxylase, evolved 3-4 billion years ago in an anaerobic, high CO(2) atmosphere. The combined effect of low CO(2) and high O(2) levels in the modern atmosphere, and the inability of Rubisco to distinguish completely between CO(2) and O(2), leads to the occurrence of an oxygenation reaction that reduces the efficiency of(More)
C4 plants are directly affected by all major global change parameters, often in a manner that is distinct from that of C3 plants. Rising CO2 generally stimulates C3 photosynthesis more than C4, but C4 species still exhibit positive responses, particularly at elevated temperature and arid conditions where they are currently common. Acclimation of(More)
To examine the role of acclimation versus adaptation on the temperature responses of CO2 assimilation, we measured dark respiration (R n) and the CO2 response of net photosynthesis (A) in Populus balsamifera collected from warm and cool habitats and grown at warm and cool temperatures. R n and the rate of photosynthetic electron transport (J) are(More)
The CO2-fixing enzyme Rubisco plays a crucial biological role as a primary determinant of both plant yield and the response of the biosphere to global change. Here, we describe techniques for measuring the amount and activity of Rubisco in higher plants. To accommodate a range of experimental capabilities, we describe basic radioisotopic methods as well as(More)
Photosynthetic acclimation varies among species, which likely reveals variations at the biochemical level in the pathways that constitute carbon assimilation and energy transfer. Local adaptation and phenotypic plasticity affect the environmental response of photosynthesis. Phenotypic plasticity allows for a wide array of responses from a single individual,(More)