EFFECTS OF RIBULOSE 1,5 BISPHOSPHATE CARBOXYLASE/OXYGENASE CONTENT, LEAF NITROGEN AND LEAF MORPHOLOGY ON CO₂ ASSIMILATION IN STRAWBERRY GENOTYPES

RCP37, a clonal ecotype of wild strawberry (Fragaria chiloensis) with extremely high Photosynthetic Nitrogen Use Efficiency (PNUE) was compared to a standard cultivar of strawberry ‘Midway’ (Fragaria X ananassa Duchn.) to determine if any parameters of leaf nitrogen (leaf N), leaf Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) enzyme content, Rubisco activity, leaf morphology, or plant gas exchange might explain the high PNUE of RCP37. RCP37 has higher rates of CO₂ assimilation (A) (16.1 to 13.5 μmol m^-2 s^-1), residual conductance (g’_r) (62.7 to 48.5 mmol CO₂ m^-2 s^-1), and mesophyll conductance (g’_m) (87.5 to 62.1 mmol CO₂ m^-2s^-1) compared to the cultivar ‘Midway’. RCP37 had greater amounts of Rubisco (1286.9 to 854.9 mg m^-2), and leaf N (148.5 to 96.2 mmol m^-2) than ‘Midway’, whereas there was no difference in Rubisco specific activity between these genotypes.
Leaf morphological features of thickness and A^mes/A (ratio of mesophyll area to leaf area) were also significantly higher in RCP37 compared to ‘Midway’. These results suggest to us that RCP37 has a high capacity to store excess leaf N in the form of Rubisco protein and this likely is the major factor contributing to the high PNUE of this strawberry clone.
Additionally we suggest that a simply measured parameter such as leaf protein, leaf N, or residual conductance might be used to select for high photosynthetic capacity in segregating strawberry populations where clones that have high PNUE such as RCP37 are used as a parent.

International Symposium on Growth and Development of Fruit Crops

E. Fallahi, Y. Huang, J.W. Moon Jr, R. Jensen

Rubisco, Photosynthesis, Nitrogen use efficiency, strawberry, Fragaria chiloensis, Fragaria X ananassa

https://doi.org/10.17660/ActaHortic.2000.527.21