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Mesophyll conductance plays a central role in leaf functioning of Oleaceae species exposed to contrasting sunlight irradiance
Author(s) -
Fini Alessio,
Loreto Francesco,
Tattini Massimiliano,
Giordano Cristiana,
Ferrini Francesco,
Brunetti Cecilia,
Centritto Mauro
Publication year - 2016
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/ppl.12401
Subject(s) - oleaceae , biology , botany , evergreen , deciduous , acclimatization , sunlight , light intensity , irradiance , stomatal conductance , shade tolerance , ecophysiology , photosynthesis , canopy , physics , quantum mechanics , astronomy , optics
The ability to modify mesophyll conductance ( g m ) in response to changes in irradiance may be a component of the acclimation of plants to shade‐sun transitions, thus influencing species‐specific distributions along light‐gradients, and the ecological niches for the different species. To test this hypothesis we grew three woody species of the Oleaceae family, the evergreen Phillyrea latifolia (sun‐requiring), the deciduous Fraxinus ornus (facultative sun‐requiring) and the hemi‐deciduous Ligustrum vulgare (shade tolerant) at 30 or 100% sunlight irradiance. We show that neither mesophyll conductance calculated with combined gas exchange and chlorophyll fluorescence techniques ( g m ) nor CO 2 assimilation significantly varied in F. ornus because of sunlight irradiance. This corroborates previous suggestions that species with high plasticity for light requirements, do not need to undertake extensive reorganization of leaf conductances to CO 2 diffusion to adapt to different light environments. On the other hand, g m steeply declined in L. vulgare and increased in P. latifolia exposed to full‐sun conditions. In these two species, leaf anatomical traits are in part responsible for light‐driven changes in g m , as revealed by the correlation between g m and mesophyll conductance estimated by anatomical parameters ( g mA ). Nonetheless, g m was greatly overestimated by g mA when leaf metabolism was impaired because of severe light stress. We show that g m is maximum at the light intensity at which plant species have evolved and we conclude that g m actually plays a key role in the sun and shade adaptation of Mediterranean species. The limits of g mA in predicting mesophyll conductance are also highlighted.