Leaf responses to drought stress in Mediterranean accessions of Solanum lycopersicum: anatomical adaptations in relation to gas exchange parameters.
In a previous study, important acclimation to water stress was observed in the Ramellet tomato cultivar (TR) from the Balearic Islands, related to an increase in the water-use efficiency through modifications in both stomatal (g(s)) and mesophyll conductances (g(m)). In the present work, the comparison of physiological and morphological traits between TR accessions grown with and without water stress confirmed that variability in the photosynthetic capacity was mostly explained by differences in the diffusion of CO2 through stomata and leaf mesophyll. Maximization of gm under both treatments was mainly achieved through adjustments in the mesophyll thickness and porosity and the surface area of chloroplasts exposed to intercellular airspace (S(c)). In addition, the lower g(m) /S(c) ratio for a given porosity in drought-acclimated plants suggests that the decrease in gm was due to an increased cell wall thickness. Stomatal conductance was also affected by drought-associated changes in the morphological properties of stomata, in an accession and treatment-dependent manner. The results confirm the presence of advantageous physiological traits in the response to drought stress in Mediterranean accessions of tomato, and relate them to particular changes in the leaf anatomical properties, suggesting specific adaptive processes operating at the leaf anatomical level.
Research Group on Plant Biology under Mediterranean Conditions, Department of Biology, Universitat de les Illes Balears, Carretera de Valldemossa km 7.5, 07122 Palma, Spain. jeroni.galmes@uib.cat
Jeroni
J
Galmés
Joan Manuel
JM
Ochogavía
Jorge
J
Gago
Emilio José
EJ
Roldán
Josep
J
Cifre
Miquel Àngel
MÀ
Conesa
D000064:Acclimatization; D002245:Carbon Dioxide / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism; D003681:Dehydration; D004058:Diffusion; D055864:Droughts; D005740:Gases / Q000378:metabolism; D018551:Solanum lycopersicum / Q000033:anatomy & histology / Q000502:physiology*; D058503:Mesophyll Cells / Q000502:physiology; D018515:Plant Leaves / Q000033:anatomy & histology* / Q000502:physiology; D054046:Plant Stomata / Q000033:anatomy & histology / Q000502:physiology; D018526:Plant Transpiration; D016062:Porosity
D005740:Gases; D002245:Carbon Dioxide