Analysis of the O₂ dependency in leaf‐level photosynthesis of two Reynoutria japonica populations growing at different altitudes

Abstract

To examine the effects of decreased CO 2 and O 2 partial pressure on leaf-level photosynthesis in alpine plants at high altitude, we compared the maximal carboxylation efficiency, CE , of Reynoutria japonica Houtt. var. japonica growing in a highland with one growing in a lowland. CE under the native atmospheric conditions (native CE ) of the highland population was significantly lower than that of the lowland one. The O 2 dependency of CE was significantly less in the highland population than in the lowland. Using theoretical analysis, we explained that O 2 dependency of leaf-level photosynthesis became less as internal conductance ( g i ) decreased. We also showed that g i and the content of active Rubisco ( E ) could be estimated from the O 2 dependency of leaf-level photosynthesis. By applying the analysis, a severe limitation of CO 2 diffusion in the leaf was estimated in the highland population, whereas almost the same values of E were estimated in both populations. A reasonable explanation for the difference in the native CE is the smaller O 2 dependency and photosynthetic capacity caused by a smaller g i in the highland population in addition to the differences in the partial pressures of CO 2 and O 2 .

Temperature Influences Carbon Accumulation in Moist Tropical Forests

“…Declining pressure does not alter the molar ratio of CO 2 in the atmosphere, but does cause a decline in the partial pressure of atmospheric CO 2 , which could diminish photosynthesis rates at higher elevations (e.g., Gale 1972, 2004, Friend and Woodward 1990. However, increases in the diffusivity of CO 2 partially offset decreases in CO 2 partial pressure, and concomitant declines in O 2 partial pressures lead to lower rates of photorespiration in C 3 plants at high elevations (Terashima et al 1995, Sakata andYokoi 2002). Overall differences in leaf photosynthetic capacity among high-and low-elevation plants are small (e.g., Kö rner and Diemer 1987, Cordell et al 1999).…”

The Biology of Invasive Alien Plants in Canada. 5. Polygonum cuspidatum Sieb. & Zucc. [= Fallopia japonica (Houtt.) Ronse Decr.]

“…and lowland (100 m a.s.l.) P. cuspidatum populations from Japan at native atmospheric conditions (Sakata and Yokoi 2002). The lowland ecotype had higher carboxylation efficiency (µmol CO 2 m -2 s -1 per µmol CO 2 mol -1 ) than the highland ecotype at their respective native atmospheric conditions (22% lower CO 2 and O 2 partial pressures in highland environment).…”

Eco-physiological variations in three Mediterranean coppices along an altitudinal gradient

“…Tra queste, numerose ipotesi sono state proposte per spiegare tali variazioni; ad esempio alcuni studi hanno osservato che elevate concentrazioni di azoto fogliare presenti su piante di alta quota mostravano un incremento dell'efficienza carbossilativa e un basso rapporto tra pressioni parziali intercellulari e atmosferiche (p i /p a - Field & Mooney 1986, Evans 1989, Morecroft et al 1992. Ulteriori interpretazioni includono le differenze della composizione atmosferica (pressioni parziali della CO 2 e dell'O 2 ) osservate con l'au-mento della quota altimetrica che può alterare la diffusione della CO 2 verso i siti di carbossilazione a causa della resistenza stomatica e del mesofillo (Woodward 1986, Körner et al 1991, Terashima et al 1995, Kogami et al 2001, Sakata & Yokoi 2002.…”