The photosynthetic characteristics of differently shaped leaves in Populus euphratica Olivier |
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Authors: | HL Wang SD Yang and CL Zhang |
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Institution: | (1) Department of Biology, Lanzhou University, Lanzhou, Gansu, 730000, P.R, China |
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Abstract: | There is a distinct leaf shape polymorphism within a single plant of P. euphratica Olivier. The anatomical structure, carbon isotope discrimination (Δ13C), and stomatal and photosynthetic behaviour were investigated in broad-ovate (BOL) and lanceolate (LL) leaves, located at
the top and bottom in crown, respectively, of a mature Euphrates poplar growing in its native habitat. Both types of leaves
had a non-Kranz anatomy and low Δ13C values. However, Δ13C of a LL was in average 3.2‰ larger than that of a BOL. In comparison with the LL, the BOL had a smaller stomatal conductance,
causing subsequent decreases in transpiration rate and ratio of CO2 concentrations in intercellular spaces to air. Carbon assimilation rate and water use efficiency were higher in the BOLs
than in the LLs. The BOL exhibited C4-like enzymological features, the activity of glycollate oxidase, and the ratio of activities of ribulose-1,5-bisphosphate
carboxylase (RuBPC) to phosphoenolpyruvate carboxylase (PEPC) was lower in BOL than in LL throughout the whole growing season.
The lowered ratio of RuBPC/PEPC in BOL was mainly associated with a marked decline in the activity of RuBPC, and only a slight
increase in the activity of PEPC. These differences might contribute to microclimate adaptation in both types of leaves.
This revised version was published online in June 2006 with corrections to the Cover Date. |
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Keywords: | broad-ovate leaf Δ 13C glycollate oxidase lanceolate leaf leaf morphology and anatomy phosphoenolpyruvate carboxylase polymorphism poplar ribulose-1 5-bisphosphate carboxylase/oxygenase |
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