Photosynthetic capacity is negatively correlated with the concentration of leaf phenolic compounds across a range of different species.
OBJECTIVE
Phenolic compounds are the most commonly studied of all secondary metabolites because of their significant protective-defensive roles and their significant concentration in plant tissues. However, there has been little study on relationships between gas exchange parameters and the concentration of leaf phenolic compounds (total phenolics (TP) and condensed tannins (CT)) across a range of species. Therefore, we addressed the question: is there any correlation between photosynthetic capacity (A(max)) and TP and CT across species from different ecosystems in different continents?


METHODS
A plethora of functional and structural parameters were measured in 49 plant species following different growth strategies from five sampling sites located in Greece and Australia. The relationships between several leaf traits were analysed by means of regression and principal component analysis.


RESULTS
The results revealed a negative relationship between TP and CT and A(max) among the different plant species, growth strategies and sampling sites, irrespective of expression (with respect to mass, area or nitrogen content). Principal component analysis showed that high concentrations of TP and CT are associated with thick, dense leaves with low nitrogen. This leaf type is characterized by low growth, A(max) and transpiration rates, and is common in environments with low water and nutrient availability, high temperatures and high light intensities. Therefore, the high TP and CT in such leaves are compatible with the protective and defensive functions ascribed to them.


CONCLUSIONS
Our results indicate a functional integration between carbon gain and the concentration of leaf phenolic compounds that reflects the trade-off between growth and defence/protection demands, depending on the growth strategy adopted by each species.
Laboratory of Plant Physiology, Department of Agricultural Biotechnology ,  Agricultural University of Athens ,  Iera Odos 75, Votanikos, 11855 Athens ,  Greece.
Sally
S
Sumbele
Mariangela N
MN
Fotelli
Dimosthenis
D
Nikolopoulos
Georgia
G
Tooulakou
Vally
V
Liakoura
Georgios
G
Liakopoulos
Panagiota
P
Bresta
Elissavet
E
Dotsika
Mark A
MA
Adams
George
G
Karabourniotis