To measure major vein density we scanned whole leaves and used Image J software, classifying vein order by color scheme (Fig.4) For minor vein density, leaf portions were cleared with NaOH 15% and stained with Safranin 1% (Fig.5) or with Toluidine blue 0,5% (Fig.6). Optical microscope images were then used to measure vein density with the same method. Leaf water relation traits in typical Sicilian varieties of Vitis vinifera L. S. Inzerillo 1 , E. Oddo 1 , L. Pollina 1 , L. Abbate 2 , F. Carimi 2 , M. Sajeva 1 , A. Nardini 3 1 Dept STEBICEF, University of Palermo, via Archirafi 20, Palermo, Italy 2 Institute of Biosciences and BioResources-CNR, Corso Calatafimi 414, Palermo, Italy 3 Dept Scienze della Vita, University of Trieste, via Giorgieri 10, Trieste, Italy simone.inzerillo@unipa.it Sicily represents one of the most significant regions for grapevine cultivation and wine production. The high number of autochthonous grapevine varieties is an important source of genetic diversity. The many Sicilian varieties have anatomical and physiological traits that allow them to resist to different levels of drought stress and achieve different levels of productivity. Leaf vasculature plays crucial roles in transport and mechanical support, and leaf vein architecture and density affect photosynthesis via hydraulic efficiency (1). We are studying four Sicilian grapevines cultivars, Nero d’Avola, Corinto, Catarratto and Zibibbo, their responses to drought conditions in terms of water relations and their leaf hydraulic architecture. The plants were grown in the experimental field of the IBBR-CNR near Palermo, Italy, under rain-fed conditions. Measurements were conducted during the summer from 2011 to 2013. We followed the water relations of the four cultivars through daily patterns of leaf water potential, Ψ L (Fig.1) and stomatal conductance, g s (Fig.2), measured with a Scholander pressure chamber (PMS 1505D) and a leaf porometer (Decagon SC-1), respectively . We constructed pressure-volume curves by the bench dehydration technique (2) to obtain leaf water potential at turgor loss point (Ψ tlp ), osmotic potential at full rehydration (π 0 ), bulk modulus of elasticity, ε max (Table 1) and Höfler diagrams (Fig.3). References 1) Brodribb T. et al. (2007), Plant Physiology, 144, 1890- 1898. 2) Tyree M.T. & Hammel H.T. (1972) Journal of Experimental Botany, 23, 267–282. Y tlp (MPa) p 0 (MPa) e max (MPa) Nero d’Avola -1.68  0.16 a -1.26  0.05 b 12.3  2.45 a Corinto -1.65  0.02 a -1.30  0.06 ab 17.3  5.17 ab Catarratto -1.86  0.16 ab -1.42  0.11 a 22.2  7.46 b Zibibbo -2.04  0.17 b -1.60  0.11 c 24.3  5.28 b Table 1 Fig.2 Major veins density (cm -1 ) Minor veins density (mm -1 ) Free ending veins density (mm -1 ) Nero d'Avola 3.7 9.19 ± 0.98 2.46 ± 0.34 Corinto 3.52 ± 0.47 9.61 ± 0.83 2.05 ± 0.46 Catarratto 4.74 ± 0.31 9.22 ± 0.95 2.72 ± 0.65 Zibibbo 3.93 ± 0.47 9.75 ± 1.12 2.88 ± 0.45 Table 2 Fig.4 . Whole leaf of Catarratto. Fig.5. Cleared and stained portion of Nero d’Avola leaf. Fig.6. Cleared and stained portion of Zibibbo leaf. Fig.3 We found several differences among the cultivars: Corinto showed the lowest levels of g s and Ψ L . Catarratto and Zibibbo showed intermediate behavior, while Nero d’Avola showed the highest peak in g s and the less negative Ψ L values. Only Corinto reached stress conditions, while Ψ L values of the other cultivars remained well above their respective Ψ tlp . Zibibbo showed a significantly higher value of π 0 , while Nero d’Avola showed the lowest ε max value. Zibibbo and Catarratto, with higher ε max , decreased Ψ L values at lower levels of water loss than the other two cultivars. Catarratto and Zibibbo showed the overall highest vein density values (Table 2). Acknowledgements This work was funded in part by the University of Palermo (Fondi di Ateneo CUP B74G13000180001 to M.S.) View publication stats View publication stats